STOCKHOLDERS AGREEMENT

Exhibit 10.1

NETSCOUT SYSTEMS, INC.

AND THE OTHER PARTIES HERETO

STOCKHOLDERS AGREEMENT

September 19, 2007

STOCKHOLDERS AGREEMENT

This STOCKHOLDERS AGREEMENT, dated as of September 19, 2007 (this “Agreement”), is entered into among NetScout Systems, Inc. (the “ Company ”), and the undersigned Persons who are, or who are to become, stockholders of the Company. Each of such Persons, other than the Company are sometimes referred to individually as a “ Stockholder ” and together as the “ Stockholders .”

WHEREAS, concurrently herewith, the Company, Bradley Merger Sub LLC, a Delaware limited liability company and wholly-owned subsidiary of the Company (“ Merger Sub ”), Network General Central Corporation, a Delaware corporation (“ NetGen ”), and Network General Corporation, a Delaware Corporation (“ NetGen Opco ” and together with NetGen, the “ Seller Parties ”) have entered into an Agreement and Plan of Merger (as amended from time to time, the “ Merger Agreement ”), dated the date hereof, pursuant to which, subject to satisfaction or waiver of the conditions therein, Merger Sub will merge with and into NetGen (the “ Merger ”), and the Company will issue shares of its Common Stock, par value $0.001 per share (the “ Shares ”), to the Stockholders;

WHEREAS, upon consummation of the Merger, the Stockholders will Beneficially Own Shares;

WHEREAS, the parties believe that it is in the best interests of the Company and the Stockholders to provide for certain rights and obligations of the parties with respect to various corporate matters of the Company following the Merger; and

WHEREAS, the Merger Agreement contemplates that this Agreement will be executed concurrently with the execution of the Merger Agreement, with its provisions to become effective upon consummation of the Merger.

NOW, THEREFORE, in consideration of the premises and the mutual covenants and agreements of the parties hereto contained herein, and other good and valuable consideration, the receipt and sufficiency of which hereby are acknowledged, and subject to the satisfaction or waiver of the conditions hereof, the parties hereto agree as follows:

ARTICLE I.

INTRODUCTORY MATTERS

1.1. Defined Terms .

In addition to the terms defined elsewhere herein, the following terms have the following meanings when used herein with initial capital letters:

“ 13D Group ” means a “group” as such term is used in Section 13(d)(3) of the Exchange Act.

“ AAA ” has the meaning given to that term in Section 7.9 of this Agreement.

“ Affiliate ” has the meaning given to that term in Rule 405 promulgated under the Securities Act; provided that (a) officers, Directors or employees of the Company will not be deemed to be Affiliates of a Stockholder for purposes hereof solely by reason of being officers, Directors or employees of the Company; (b) for purposes of Article II, none of the investment fund Affiliates of any Stockholder or any of the portfolio companies in which any Stockholder or any of its investment fund Affiliates have made a debt or equity investment shall be considered Affiliates of such Stockholder, unless (i) such Stockholder has provided material non-public information with respect to the Company and its Subsidiaries to such investment fund Affiliate or portfolio company or (ii) such Stockholder has expressly directed such investment fund Affiliate or portfolio company to take an action that would be restricted by Article II if it had been taken by such Stockholder; and (c) for purposes of this Agreement (other than Article II), none of the portfolio companies in which any Stockholder or any of its investment fund Affiliates have made a debt or equity investment shall be considered Affiliates of such Stockholder.

“ Agreement ” means this Agreement, as the same may be amended, supplemented or otherwise modified from time to time in accordance with the terms hereof.

“ Assumption Agreement ” means a writing substantially in the form of Exhibit A hereto whereby a Permitted Transferee or other Transferee pursuant to Sections 3.22 becomes a party to, and agrees to be bound to the same extent as its Transferor by, the terms of this Agreement.

“ Beneficial Owner ,” “ Beneficially Own ,” “ Beneficial Ownership ” and words of similar import have the meanings ascribed to such terms in Rule 13d-3 under the Exchange Act. Without duplicative counting of the same securities by the same holder, securities “Beneficially Owned” by a Person includes securities “Beneficially Owned” by all other Persons with whom such Person would constitute a 13D Group with respect to securities of the same issuer. Notwithstanding anything to the contrary set forth in this Agreement, no Stockholder is to be deemed to Beneficially Own any securities of the Company held by any other Stockholder solely by virtue of the provisions of this Agreement.

“ Board ” means the Board of Directors of the Company.

“ Business Day ” means a day other than a Saturday, Sunday, federal or Massachusetts or California state holiday, or other day on which commercial banks in Massachusetts or California are authorized or required by law to close.

“ Change of Control of the Company ” shall mean any of the following: (i) a merger, consolidation or other business combination or transaction to which the Company is a party if the shares of Voting Stock outstanding immediately prior to the effective date of such merger, consolidation or other business combination or transaction do not represent (or the shares of Voting Stock into which they are converted or exchanged pursuant to such merger, consolidation or other business combination or transaction do not represent) 50% or more of the Total Current Voting Power of the surviving corporation (or its parent corporation) following such merger, consolidation or other business combination or transaction; (ii) an acquisition by any Person (other than the Stockholder and their Affiliates or any 13D Group of which any of them is a

- 2 -

member) of beneficial ownership of Voting Stock representing 50% or more of the Total Current Voting Power of the Company following such acquisition, (iii) a sale of all or substantially all the consolidated assets of the Company to any Person or Persons (other than the Stockholders and their Affiliates or any 13D Group of which any of them is a member); or (iv) a liquidation or dissolution of the Company.

“ Closing Date ” has the meaning set forth in the Merger Agreement.

“ Common Stock ” means the Common Stock, par value $0.001 per share, of the Company.

“ Control ,” “ Controlled ,” “ Controlling ,” and “ Under Common Control With ” have the meanings ascribed to such terms in Rule 12b-2 under the Exchange Act.

“ Demand Party ” has the meaning given to that term in Section 4.2(a) of this Agreement.

“ Demand Registration ” has the meaning given to that term in Section 4.2(a) of this Agreement.

“ Director ” means any member of the Board.

“ Exchange Act ” means the Securities Exchange Act of 1934, as amended, and the rules and regulations promulgated thereunder, as the same may be amended from time to time.

“ Holder ” has the meaning given to that term in Section 4.5 of this Agreement.

“ Indemnified Parties ” has the meaning given to that term in Section 4.5 of this Agreement.

“ Initial Share Holding Period ” has the meaning given to that term in Section 0 of this Agreement.

“ Initiating Holder ” has the meaning given to that term in Section 4.1(a) of this Agreement.

“ Legend ” has the meaning given to that term in Section 3.3(d) of this Agreement.

“ Lien ” means, with respect to any property or asset, any mortgage, pledge, security interest, lien (statutory or other), charge, encumbrance or other similar restrictions or limitations of any kind or nature whatsoever on or with respect to such property or asset.

“ Marketed Underwritten Take-Down ” means any Underwritten Take-Down that involves a customary “road show” (including an “electronic road show”) or other substantial marketing effort by the underwriters over a period of at least 48 hours.

“ Merger ” has the meaning given to that term in the recitals of this Agreement.

“ Merger Agreement ” has the meaning given to that term in the recitals of this Agreement.

- 3 -

“ NetGen Stock ” means shall mean all shares of NetGen’s capital stock authorized, issued or outstanding prior to the consummation of the Merger, of whatever class or series, including all of the Common Stock, $0.01 par value per share, of NetGen.

“ NetGen Stock Option ” means any options, warrants, stock appreciation rights, convertible debt or other rights (contingent and other, vested or unvested) to purchase or otherwise acquire, equity securities of NetGen or any NetGen Subsidiary or any phantom stock, stock appreciation rights or other derivative instrument or right to payment related to such equity securities.

“ NetGen Subsidiary ” means any Subsidiary of NetGen, including without limitation NetGen Opco.

“ Permitted Transferee ” means, in the case of any Stockholder, (A) any Affiliate (other than an individual) of such Stockholder, (B) any stockholder, general or limited partner, director, officer, managing or non-managing member or employee of such Stockholder and the direct and indirect owners of any of the foregoing entities, (C) the heirs, executors, administrators, testamentary trustees, legatees or beneficiaries of any of the individuals referred to in clause (B), (D) for estate planning purposes, any trust, the beneficiaries of which include only (1) such Stockholder, (2) Permitted Transferees referred to in clauses (A), (B) and (C) and (3) spouses (including former spouses) and lineal descendants (including by adoption) of Permitted Transferees referred to in clause (B), and (E) a corporation, partnership, limited liability company or similar entity, a majority of the equity of which is owned and Controlled by such Stockholder and/or Permitted Transferees referred to in clauses (A), (B), (C) and (D).

“ Person ” means any individual, corporation, limited liability company, partnership, trust, joint stock company, business trust, unincorporated association, joint venture, governmental authority or other legal entity of any nature whatsoever.

“ Prior Shelf Registration Statement ” means, collectively, the Company’s Registration Statement on Form S-3, File No. 333-145047, and any registration statement filed pursuant to Rule 462(b) of the Securities Act with respect thereto.

“ Public Offering ” means the sale of any class of capital stock of the Company to the public pursuant to an effective registration statement (other than a registration statement on Form S-4 or S-8 or any similar or successor form) filed under the Securities Act.

“ Registrable Securities ” means (i) the Shares that are issued to the Stockholders pursuant to the Merger Agreement and (ii) any Shares or other securities which may be issued, converted, exchanged or distributed in respect of the Shares that are issued to the Stockholders pursuant to the Merger Agreement by way of merger, consolidation, tender offer, stock dividend, stock split, asset sale or other distribution, recapitalization or reclassification. For purposes of this Agreement, with respect to any Stockholder, any Registrable Securities held by such Stockholder will cease to be Registrable Securities when (A) a registration statement covering such Registrable Securities has been declared effective and such Registrable Securities have been disposed of pursuant to such effective registration statement, (B) such Registrable Securities

- 4 -

shall have been offered and sold pursuant to Rule 144 or Rule 145 (or any similar provisions then in effect) under the Securities Act, (C) all Registrable Securities held by such Stockholder and its Affiliates (i) equal, in the aggregate, less than 5% of the outstanding Common Stock and (ii) are eligible for transfer to the public pursuant to Rule 144 or Rule 145 (or any similar provisions then in effect) under the Securities Act (without restriction as to manner of sale or amount sold) during any three-month period, (D) such Registrable Securities are Transferred by a Person in a transaction in which rights under the provisions of this Agreement are not assigned in accordance with this Agreement, or (E) such Registrable Securities cease to be outstanding.

“ Registration Expenses ” means any and all expenses of the Company in connection with any registration that is subject to Sections 4.1 or 4.2, including without limitation (i) all SEC, stock exchange, and National Association of Securities Dealers, Inc. (the “ NASD ”) registration and filing fees (including, if applicable, the fees and expenses of any “qualified independent underwriter,” as such term is defined in Rule 2720 of the NASD, and of its counsel), (ii) all fees and expenses of complying with securities or blue sky laws (including fees and disbursements of counsel for the underwriters in connection with blue sky qualifications of the Registrable Securities), (iii) all printing, messenger and delivery expenses, (iv) all fees and expenses incurred in connection with the listing of the Registrable Securities on any securities exchange and all rating agency fees, (v) the fees and disbursements of counsel for the Company and of its independent public accountants, including the expenses of any Special Audits and/or “cold comfort” letters required by or incident to such performance and compliance, (vi) any fees and disbursements of underwriters customarily paid by the issuers or sellers of securities, but excluding underwriting discounts and commissions and transfer taxes, if any, (vii) the reasonable fees and disbursements of counsel selected pursuant to Section 4.7 in connection with such registration; provided , however , that such fees and disbursements do not exceed $40,000 in connection with such registration (in which case, such excess shall not be deemed a “Registration Expense”); and (viii) the costs and expenses of the Company relating to analyst and investor presentations or any “road show” undertaken in connection with any registration and/or marketing of the Registrable Securities, provided that, subject to the obligations of the Company set forth in Section 4.3(r), nothing in this clause (viii) shall obligate the Company to engage or participate in any such presentations or road show.

“ Registration Rights Holders ” means, collectively, (i) the Stockholders, and (ii) to the extent permitted by Section 4.9, the assignees of such Stockholders.

“ SEC ” means the Securities and Exchange Commission.

“ Securities Act ” means the Securities Act of 1933, as amended, and the rules and regulations promulgated thereunder, as the same may be amended from time to time.

“ Shares ” has the meaning given to that term in the recitals to this Agreement.

“ Shelf Registration Statement ” shall have the meaning given to such term in Section 4.2(a) of this Agreement.

- 5 -

“ Significant Event ” has the meaning given to that term in Section 2.2(b) of this Agreement.

“ SLP Stockholder ” means (i) Silver Lake Partners, L.P. and each other Stockholder that is an Affiliate of Silver Lake Partners, L.P. and (ii) to the extent any Registrable Securities are Transferred by any such Stockholder to any of its Permitted Transferees, each such Permitted Transferee if it executes and delivers an Assumption Agreement.

“ Special Audit ” means an audit of the Company other than the regular audit conducted by the Company at the end of its fiscal year.

“ Sponsor ” means Silver Lake Partners, L.P. or TPG Starburst IV, LLC, and “ Sponsors ” means Silver Lake Partners, L.P. and TPG Starburst IV, LLC, collectively.

“ Stockholder ” has the meaning given to that term in the recitals to this Agreement.

“ Stockholder Representatives ” has the meaning given to that term in Section 5.1 of this Agreement.

“ Subsidiary ” shall mean, in respect of any specified Person, any corporation or other entity of which 50% or more of the outstanding share capital or other equity interest is owned, directly or indirectly, by such specified Person.

“ Suspension Period ” has the meaning given to that term in Section 4.2(a) of this Agreement.

“ Total Current Voting Power ” means, with respect to any corporation, the total number of votes which may be cast in the election of members of the board of directors of the corporation if all securities entitled to vote in the election of such directors are present and voted.

“ TPG Stockholders ” means (i) each Stockholder that is an Affiliate of TPG Capital, L.P. and (ii) to the extent any Registrable Securities are Transferred by any such Stockholder to any of its Permitted Transferees, each such Permitted Transferee if it executes and delivers an Assumption Agreement.

“ Transfer ” means, with respect to any Share (or direct or indirect economic or other interest therein), a transfer, distribution, sale, gift, assignment, pledge, hypothecation or other disposition, whether directly or indirectly (pursuant to the creation of a derivative security or otherwise), the grant of an option or other right or the imposition of a restriction on disposition or voting or by operation of law; provided that any transfer of limited partnership, limited liability company or other ownership interests in the Sponsors or any of their respective Affiliates or Permitted Transferees shall not be deemed to be a “Transfer.” When used as a verb, “Transfer” shall have the correlative meaning. In addition, “Transferred”, “Transferee” and “Transferring” shall have the correlative meanings.

“ Underwritten Shelf Take-Down ” means an offering or sale of Registrable Securities pursuant to a Shelf Registration Statement that is underwritten.

- 6 -

“ Voting Stock ” means the Shares and any other securities of the Company entitled to vote generally in the election of Directors of the Company.

1.2. Construction .

The language used in this Agreement will be deemed to be the language chosen by the parties to express their mutual intent, and no rule of strict construction will be applied against any party. Unless the context otherwise requires: (a) “or” is disjunctive but not exclusive, (b) words in the singular include the plural, and in the plural include the singular, (c) the words “hereof”, “herein” and “hereunder” and words of similar import when used in this Agreement refer to this Agreement as a whole and not to any particular provision of this Agreement, and Section and Exhibit references are to this Agreement unless otherwise specified and (d) whenever the words “include,” “includes” or “including” are used in this Agreement, they shall be deemed to be followed by the words “without limitation.”

ARTICLE II.

STANDSTILL PROVISIONS

2.1. Restrictions .

Except to the extent approved by a majority of the Directors, excluding the Stockholder Representatives, subject to the provisions of Section 2.2 hereof, each Stockholder agrees, severally and not jointly, that such Stockholder shall not, and it shall cause its Affiliates not to, directly or indirectly:

(a) purchase or acquire, or offer or agree to purchase or acquire, directly or indirectly, alone or in concert with any other Person, by purchase, gift or otherwise, Beneficial Ownership of any Voting Stock of the Company if such acquisition would result in the Stockholders and their Affiliates Beneficially Owning more than the number of Shares (subject to adjustment for any events set forth in clause (B) below) such Stockholders and their Affiliates collectively Beneficially Own upon consummation of the Merger, except (A) as specifically contemplated by the Merger Agreement, (B) by way of stock dividends or distributions, rights offerings, stock-splits, reclassifications, recapitalizations, changes in capitalization, consolidations, restructurings, business combinations, exchange offers, reorganizations or any other similar action taken by the Company, or (C) for equity-based awards granted to any Stockholder or Affiliate thereof solely in such Person’s capacity as a Director or employee of the Company;

(b) join or in any way participate in or encourage the formation of any 13D Group with respect to the Beneficial Ownership of Voting Stock of the Company with any Person who is not, immediately prior to the time of formation of such 13D Group, (i) another Stockholder or (ii) an Affiliate of (A) such Stockholder or another Stockholder or (B) any other Person which is then a member of a 13D Group with such Stockholder or another Stockholder;

- 7 -

(c) (i) make, or in any way participate in, directly or indirectly, alone or in concert with any other Person, any “solicitation” of “proxies” (as such terms are defined or used in Regulation 14A under the Exchange Act), including participation in any election contest, or (ii) otherwise communicate with the stockholders of the Company (other than (x) another Stockholder, (y) an Affiliate of such Stockholder, or (z) any other Person which is then a member of a 13D Group with such Stockholder or another Stockholder) in connection with or in relation to a proxy solicitation; provided , that the limitation contained in this clause (c) shall not apply to any proposal relating to a Change of Control of the Company to be voted on by the Company’s stockholders that is not instituted or proposed by such Stockholder or any Affiliate of such Stockholder or any 13D Group of which such Stockholder or any Affiliate of such Stockholder is a member;

(d) advise or seek to influence any Person (other than (i) another Stockholder, (ii) Affiliates of such Stockholder or another Stockholder or (iii) Persons who are members of any 13D Group of which such Stockholder or another Stockholder is member and which does not violate Section 2.1(b) above), with respect to the voting of any Voting Stock;

(e) initiate or propose one or more stockholders’ proposals, as described in Rule 14a-8 under the Exchange Act, with respect to the Company;

(f) call, request or otherwise attempt to convene or cause management of the Company to convene a meeting of the stockholders of the Company;

(g) initiate, propose or solicit any proposal with respect to any merger, consolidation or business combination involving the Company, any tender or exchange offer for equity securities of the Company, any sale or purchase of a substantial amount of the assets of the Company, any purchase of Voting Stock of the Company (other than as permitted in Section 2.1(a) above), any dissolution, liquidation, reorganization or recapitalization or similar business transaction involving the Company;

(h) deposit any shares of Voting Stock of the Company in a voting trust or subject any such Voting Stock to any arrangement or agreement with respect to the voting of such Voting Stock (other than arrangements or agreements solely involving (i) another Stockholder, (ii) Affiliates of such Stockholder or another Stockholder or (iii) Persons who are members of any 13D Group of which such Stockholder or another Stockholder is member and which does not violate Section 2.1(b) above);

(i) seek to place a representative on the Board or remove any Board members; except with respect to the Stockholders’ Board appointment rights provided by Section 5.1;

(j) propose publicly (or in a manner reasonably expected to result in public disclosure) to do, announce an intention to do, or enter into any arrangement or understanding with any other Person to do, any of the actions restricted or prohibited under this Section 2.1; or

(k) propose publicly (or in a manner reasonably expected to result in public disclosure) any proposal to amend or terminate the provisions of this Section 2.1;

- 8 -

provided that nothing in this Section 2.1 shall (i) prohibit or restrict any Stockholder or its Affiliates from taking any action required or contemplated by any other provision of this Agreement or the Merger Agreement, (ii) prohibit any individual who is serving as a Director of the Company, solely in his or her capacity as such Director, from taking any action or making any statement in such capacity, (iii) prohibit any individual who is serving as an Officer or employee of the Company, solely in his or her capacity as such, from performing his or her duties in such capacity or from participating in the employee stock purchase program (if any) of the Company in which such individual is eligible to participate by virtue of such capacity, or (iv) restrict any disclosure or statements required to be made by any Stockholder or its Affiliates under applicable law to the extent any such requirement does not arise from actions by such Stockholder in violation of this Agreement. Notwithstanding anything to the contrary set forth herein, if the Board has engaged in any discussions or negotiations with, or provided any information to, any Person other than a Stockholder or any Affiliate thereof or any 13D Group of which such Stockholder is a member with respect to a potential Change of Control of the Company (or a transaction of the type that, if consummated, would result in a Change of Control of the Company) and provided the Board has not determined to terminate all such discussions, negotiations and provision of information within 20 days of the commencement of such discussion, negotiations and provisions of information, then, for so long as such condition continues to apply, such Stockholder and its Affiliates may make a private offer to effect a Change of Control of the Company to the Board that neither such Stockholder nor any of its Affiliates (i) publicly discloses or (ii) takes any action which would reasonably be expected to require the Company to publicly disclose such offer.

2.2. Suspension and Termination of Standstill Restrictions .

(a) Upon the occurrence of a Significant Event (as defined below), the restrictions set forth in Section 2.1 shall be suspended.

(b) “ Significant Event ” means any of the following:

(i) the Company enters into an agreement for, or makes a public announcement of its intention to pursue, (A) the sale or other disposition of a majority or more of the Company’s outstanding Shares, (B) the sale or disposition of all or substantially all of the Company’s assets or a similar sale or change of control transaction, or (C) any merger, consolidation, or other similar business combination that could result in a Change of Control of the Company; or

(ii) the public announcement of a bona fide proposal by a third party or 13D Group (other than the Company, a Stockholder, or any Person who is then an Affiliate of a Stockholder) to acquire Voting Stock of the Company (including pursuant to a tender or exchange offer or merger), which, if successful, would result in a Change of Control of the Company; provided, however, that the Board either (A) has approved or recommended that the stockholders of the Company accept such offer or (B) has not rejected or recommended that the stockholders of the Company refrain from accepting such offer; or

(iii) a third party or 13D Group successfully consummates a proposal of the type described in the foregoing clause 2.2(b)(ii); or

- 9 -

(iv) the adoption by the Board of a plan of liquidation or dissolution.

(c) Upon the cessation of the event or events that lead to the suspension of the restrictions in Section 2.1 pursuant to this Section 2.2, those restrictions shall be reinstated in accordance with their terms unless this Agreement has been terminated in accordance with Section 7.1.

(d) The restrictions set forth in Section 2.1 shall terminate with respect to (i) all Stockholders, upon a Change of Control of the Company, and (ii) each Stockholder, such time as such Stockholder and its Affiliates Beneficially Own less than five percent (5%) of the Company’s outstanding Common Stock.

ARTICLE III.

TRANSFER RESTRICTIONS; CERTAIN DISTRIBUTIONS

3.1. Limitations on Transfer .

During the six-month period following the Closing Date (such period, the “ Initial Share Holding Period ”), the Stockholders, severally and not jointly, agree not to Transfer any Shares received by it on the Closing Date, except that the Stockholders may make:

(a) Transfers of Shares by any Stockholder to its Permitted Transferees pursuant to Section 3.2 below;

(b) Transfers of Shares pursuant to (x) any stock repurchase program of the Company or any of its Subsidiaries, (y) any tender or exchange offer commenced under the Exchange Act, or (z) any merger, consolidation, sale, other business combination transaction, reclassification, reorganization, recapitalization or other transaction in which stockholders of the Company are offered, permitted or required to participate as holders of the Common Stock; and

(c) Transfers pursuant to Section 4.1.

3.2. Transfer to Permitted Transferees .

(a) During the Initial Share Holding Period, any Stockholder may Transfer any or all of the Shares held by it to any Permitted Transferee of such Stockholder; provided that any such Transfer is permitted by such Stockholder’s charter, bylaws, limited partnership agreement, limited liability company agreement or other governing documents, as applicable.

(b) During the Initial Share Holding Period, each Permitted Transferee of any Stockholder to which Shares are Transferred shall, and such Stockholder shall cause such Permitted Transferee to, Transfer back to such Stockholder (or to another Permitted Transferee of such Stockholder) any Shares it owns prior to such Permitted Transferee ceasing to be a Permitted Transferee to such Stockholder if such cessation would occur during the Initial Share Holding Period.

- 10 -

(c) Any Permitted Transferee of Shares during the Initial Share Holding Period will be required, at the time of and as a condition to such Transfer, to become a party to this Agreement by executing and delivering an Assumption Agreement and, upon executing and delivering an Assumption Agreement, will be treated as a Stockholder for all purposes hereof.

3.3. Other .

(a) Any Transfer of Shares under this Agreement (other than through a Public Offering) shall not be effective unless and until the Company shall have been furnished with information reasonably requested by it (which may include an opinion from counsel) demonstrating that such Transfer is exempt from or not subject to the provisions of Section 5 of the Securities Act and any other applicable securities laws.

(b) In the event of any purported Transfer by a Stockholder of any Shares in violation of the provisions of this Agreement, such purported Transfer will be void and of no effect, and the Company will not give effect to such Transfer.

(c) The Company will be entitled to take all necessary steps to ensure that any Shares issued to the Stockholders are identified as restricted securities within the meaning of Rules 144 and 145 promulgated under the Securities Act and that any resales of such Shares will be made in accordance with an exemption from registration under the Securities Act or pursuant to an effective registration statement.

(d) Each certificate representing the Shares held by a Stockholder initially will bear a customary legend on the face thereof prescribed by the Company referencing the provisions of Article III (the “ Legend ”). The Legend will be removed by the Company, with respect to any certificate representing Shares, by the delivery of substitute certificates without such Legend at any time requested by the Stockholders after (i) the Initial Share Holding Period or (ii) the termination of the restrictions set forth in Article III.

3.4. Termination . The restrictions set forth in Article III shall terminate with respect to a Stockholder upon the earlier of (a) a Change of Control of the Company and (b) such time as such Stockholder and its Affiliates Beneficially Own less than five percent (5%) of the Company’s outstanding Common Stock.

ARTICLE IV.

REGISTRATION RIGHTS

4.1. Piggyback Rights .

(a) If the Company proposes to register any of the Shares under the Securities Act (other than a registration on Form S-4 or S-8, or any successor or other forms promulgated for similar purposes) or sell Shares in an Underwritten Take-Down pursuant to a previously filed registration statement on which Registrable Securities were included (it being understood that no Registrable Securities are or will be included on the Prior Registration Statement), whether or not for sale for its own account (other than pursuant to Section 4.2), it will, at each such time, give

- 11 -

prompt written notice to the Registration Rights Holders of its intention to do so. Upon the written request of any Registration Rights Holder made within 14 days after the receipt of any such notice (which request shall specify the number of Registrable Securities intended to be registered or disposed of by such Registration Rights Holder and all other Registration Rights Holders who are Permitted Transferees of such Registration Rights Holder), the Company will use its reasonable best efforts to effect the registration under the Securities Act, or the sale of, all Registrable Securities which each Registration Rights Holder has so requested to be registered or sold; provided that (i) if, at any time after giving written notice of its intention to register or sell any securities and prior to the effective date of the registration statement filed in connection with such registration or the pricing in connection with an Underwritten Take-Down, as applicable, the Company or any other holder of securities that initiated such registration (an “ Initiating Holder ”) shall determine for any reason not to proceed with the proposed registration or Underwritten Take-Down of the securities to be sold by it, the Company or such Initiating Holder may, at its election, give written notice of such determination to the Registration Rights Holders and, thereupon, the Company shall be relieved of its obligation to register or sell any Registrable Securities in connection with such registration or Underwritten Take-Down, and (ii) if such registration involves an underwritten offering (including any Underwritten Take-Down), the Registration Rights Holders requesting to be included in the registration or Underwritten Take-Down must sell their Registrable Securities to the underwriters selected by the Company or the Initiating Holder, as the case may be, on the same terms and conditions as apply to the Company or the Initiating Holders, as the case may be), provided , however that (x) each such Registration Rights Holder shall only be obligated to (i) make representations and warranties generally as to his, her or its respective (A) execution, delivery and performance of such underwriting agreement and the agreements contemplated thereby, (B) individual ownership of the Registrable Securities being sold pursuant to such underwriting agreement and (C) information provided by such Registration Rights Holder in writing specifically for inclusion in the prospectus and (ii) agree to provide indemnification for any liability arising out of any such representations or warranties of such Registration Rights Holder, and (y) in no event shall a Registration Rights Holder’s liability for such indemnification exceed the net proceeds received by such Holder for the sale of such Registrable Securities pursuant to such underwriting agreement.

(b) The Company will pay all Registration Expenses in connection with each registration of Registrable Securities requested pursuant to this Section 4.1.

(c) If a registration pursuant to this Section 4.1 involves an underwritten offering (including any Underwritten Take-Down) and the managing underwriter advises the Company in writing that, in its opinion, the number of Registrable Securities and other securities requested to be included in such registration or Underwritten Take-Down exceeds the number which can be sold in such offering, so as to be reasonably likely to have an adverse effect on the timing or distribution of the securities offered in such offering, then the Company will include in such registration or Underwritten Take-Down (i) first, 100% of the securities, if any, the Company proposes to sell for its own account, provided that the registration of Shares contemplated by this Section 4.1 was initiated by the Company with respect to Shares intended to be registered for sale for its own account, and (ii) second, the number of Registrable Securities requested to be included by the Registration Rights Holders, if any, in such registration or Underwritten Take-Down which in the opinion of the managing underwriter, can be sold, without having the adverse effect

- 12 -

referred to above, which number of Registrable Securities shall be allocated pro rata among all such Registration Rights Holders, based on the relative number of Registrable Securities then held by each such Registration Rights Holders. In the event that (A) the Company did not initiate the registration of securities or Underwritten Take-Down intended to be registered for sale for its own account and (B) the number of Registrable Securities entitled to registration rights with respect to such Shares, requested to be included in such registration or Underwritten Take-Down is less than the number which, in the opinion of the managing underwriter, can be sold, the Company may include in such registration or Underwritten Take-Down securities it proposes to sell for its own account up to the number of securities that, in the opinion of the underwriter, can be sold.

4.2. Demand Registration .

(a) At any time during the period commencing as of the end of the Initial Share Holding Period, upon the written request of any of SLP Stockholders holding Shares that represent at least 40% of the Registrable Securities by the SLP Stockholders or any of the TPG Stockholders holding Shares that represent at least 40% of the Registrable Securities by the TPG Stockholders (a “ Demand Party ”) requesting that the Company effect the registration under the Securities Act, which, if requested by such Demand Party, may be a “shelf” registration statement under Section 415 of the Securities Act (a “ Shelf Registration Statement ”), of all or part of such Demand Party’s Registrable Securities or an Underwritten Take-Down (a “ Demand Registration ”) and specifying the amount and intended method of disposition thereof, the Company will promptly give written notice of such requested registration or such Underwritten Take-Down to the Registration Rights Holders and other holders of securities entitled to notice of such registration or Underwritten Take-Down and thereupon will, as expeditiously as reasonably possible, file a registration statement (or, in the case of an Underwritten Take-Down, an amendment thereto or prospectus supplement) to effect the registration and sale under the Securities Act of:

(i) such Registrable Securities which the Company has been so requested to register or sell by the Demand Party; and

(ii) the Registrable Securities of other Registration Rights Holders which the Company has been requested to register or sell by written request given to the Company by the Registration Rights Holders within 14 days after the giving of such written notice by the Company to the Registration Rights Holders (which request shall specify the amount and intended method of disposition of such securities);

all to the extent necessary to permit the disposition (in accordance with the intended method thereof as aforesaid) of the Registrable Securities and such other securities so to be registered or sold; provided that the Company shall not be required (a) to effect on more than one occasion, without regard to the requesting Demand Party, the filing of a Shelf Registration Statement, (b) to effect on more than one occasion, at the request of the SLP Stockholders, either (x) the filing of a registration statement (other than a Shelf Registration Statement) providing for the registration of Registrable Securities and a fully-marketed underwritten offering thereof (including a customary road show), or (y) subject to the foregoing clause (a), the filing of a Shelf Registration Statement (if not already on file) and the completion, at any time elected by the SLP

- 13 -

Stockholders, of a Marketed Underwritten Take-Down from a Shelf Registration Statement (regardless of which Demand Party has requested such Shelf Registration Statement), or (c) to effect on more than one occasion, at the request of the TPG Stockholders, either (x) the filing of a registration statement (other than a Shelf Registration Statement) providing for the registration of Registrable Securities and a fully-marketed underwritten offering thereof (including a customary road show), or (y) subject to the foregoing clause (a), the filing of a Shelf Registration Statement (if not already on file) and the completion, at any time elected by the TPG Stockholders, of a Marketed Underwritten Take-Down from a Shelf Registration Statement (regardless of which Demand Party has requested such Shelf Registration Statement), and provided further that the Company shall not be obligated to file a registration statement relating to any registration request or complete an Underwritten Take-Down, in either case under this Section 4.2(a):

(1) within a period of 90 days after (x) the completion of an Underwritten Shelf Take-Down under a previously effective Shelf Registration Statement in which the Registration Rights Holders were provided the opportunity to sell Registrable Securities, (y) the effective date of any other type of registration statement pursuant to which the Registration Rights Holders were entitled to register and sell Registrable Securities, or (z) any offering by the Company pursuant to the Prior Registration Statement; or

(2) if the Registration Rights Holders, together with the holders of any other securities of the Company entitled to inclusion in such registration or sale, propose to sell Registrable Securities and such other securities (if any) at an aggregate price to the public of less than $5,000,000; or

(3) if with respect thereto the managing underwriter, the SEC, the Securities Act, or the form on which the