Exhibit 10.1

AMENDMENT NO. 3 TO CREDIT AGREEMENT

This Amendment No. 3 to Credit Agreement (this “ Amendment ”) dated as of May 12, 2008, is made among ATS CORPORATION , a Delaware corporation (the “ Borrower ”), BANK OF AMERICA, N.A. , a national banking association organized and existing under the laws of the United States, in its capacity as administrative agent for the Lenders (as defined in the Credit Agreement (as defined below)) (in such capacity, the “ Administrative Agent ”), each of the Lenders signatory hereto and each of the Guarantors signatory hereto.

W I T N E S S E T H:

WHEREAS , the Borrower, the Administrative Agent and the Lenders have entered into that certain Credit Agreement dated as of June 4, 2007 (as amended by Amendment No. 1 to Credit Agreement dated as of June 29, 2007, Amendment No. 2 to Credit Agreement, Limited Consent and Agreement to Increase Commitments dated as of November 9, 2007, as amended by this Amendment and as from time to time hereafter further amended, restated, supplemented or otherwise modified, the “ Credit Agreement ”; capitalized terms used in this Amendment not otherwise defined herein shall have the definition given thereto in the Credit Agreement), pursuant to which the Lenders have made available to the Borrower a revolving credit facility, including a letter of credit subfacility; and

WHEREAS , each of the Guarantors has entered into a Guaranty pursuant to which it has guaranteed the payment and performance of the obligations of the Borrower under the Credit Agreement and the other Loan Documents; and

WHEREAS, the Borrower has advised the Administrative Agent and the Lenders that it desires to amend certain provisions of the Credit Agreement as set forth below and the Administrative Agent and the Lenders signatory hereto are willing to effect such amendment on the terms and conditions contained in this Agreement; and

NOW, THEREFORE , in consideration of the premises and further valuable consideration, the receipt and sufficiency of which is hereby acknowledged, the parties hereto agree as follows:

1.                                        Amendments to Credit Agreement .  Subject to the terms and conditions set forth herein, and in reliance upon the representations and warranties of the Borrower made herein, the Credit Agreement is hereby amended as follows:

(a)                           Section 1.01 of the Credit Agreement is amended to add the following defined term thereto:

“ Net Cash Proceeds ” means with respect to the sale of any Equity Interests by the Borrower or any of its Subsidiaries, or the exercise or conversion of any warrants, options or rights with respect to such Equity Interests, the excess of (i) the sum of the cash and cash equivalents received in connection therewith over (ii) the underwriting discounts and commissions, and other out-of-pocket expenses, incurred by such Person in connection therewith.

(b)                          Section 1.01 of the Credit Agreement is amended by replacing the definitions of “ Applicable Rate ” and “ Coverage Adjustment Amount ” in their entirety with the following definitions:

“ Applicable Rate ” means, from time to time, the following percentages per annum, based upon the Consolidated Leverage Ratio as set forth in the most recent Compliance Certificate received by Agent pursuant to Section 6.02(b)(i) :

Applicable Rate

Any increase or decrease in the Applicable Rate resulting from a change in the Consolidated Leverage Ratio shall become effective as of the first Business Day of the month immediately following the date a Compliance Certificate is delivered pursuant to Section 6.02(b)  (each such day, an “ Applicable Rate Change Date ”); provided , however , that if a Compliance Certificate is not delivered  when due in accordance with such Section, then Pricing Level 4 shall apply as of the first Business Day of the month following the date such Compliance Certificate was required to have been delivered; provided further that notwithstanding the Coverage Adjustment Amount then in effect, if at any date a Coverage Adjustment Amount equal to $0 would result in the Borrower’s failure to comply with Section 6.12(a)  then Pricing Level 4 shall apply as of such date until such time as the Borrower has demonstrated that a Coverage Adjustment Amount equal to $0 would not result in such non-compliance.

“ Coverage Adjustment Amount ” means, with respect to any date occurring during each period set forth below, an amount equal to the amount set

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forth below opposite such period, but subject to adjustment pursuant to Section 6.10 :

provided , however , each of the Coverage Adjustment Amounts set forth in the table above shall be reduced by (i) the amount of any mandatory prepayment required to be made by Sections 2.05(d)  and (e) , and (ii) the Net Cash Proceeds received by the Borrower or any of its Subsidiaries in connection with the Borrower’s Early Warrant Exercise Program effective as of April 8, 2008.

(c)                                  Section 1.01 of the Credit Agreement is amended by adding the following sentence to the end of the definition of “ Consolidated Cash Flow ”:

“Amounts included in the calculation of Consolidated Cash Flow under clause (b) above for losses from discontinued operations and extraordinary items and clause (c) above for other non-cash charges shall be subject to the approval of such items by the Administrative Agent.”

(d)                                 Section 1.01 of the Credit Agreement is amended by adding the following sentence to the end of the definition of “ Consolidated EBITDA ”:

“Amounts included in the calculation of Consolidated EBITDA under clause (b) above for losses from discontinued operations and extraordinary items and clause (e) above for other non-cash charges shall be subject to the approval of such items by the Administrative Agent.”

(e)                                  Section 2.05 of the Credit Agreement is amended by adding new subsections (d) and (e) thereto as follows:

“(d)                      Upon the sale or issuance by the Borrower or any of its Subsidiaries of any of its Equity Interests (including, without limitation, any conversion or exercise by any Person of any warrants, options or rights with respect to any such Equity Interests other than in connection with the Borrower’s Early Warrant Exercise Program effective as of April 8, 2008, but not including any sales or issuances of Equity Interests to the Borrower or any Guarantor), the Borrower shall prepay an aggregate principal amount of Loans equal to (i) at any time the Consolidated Leverage Ratio is less than or equal to 2.50 to 1.00 (before giving effect to any prepayment required by this Section 2.05(d) ), 50% of the Net

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Cash Proceeds of such sale or issuance and (ii) at any time the Consolidated Leverage Ratio is greater than 2.50 to 1.00 (before giving effect to any prepayment required by this Section 2.05(d) ), 100% of the Net Cash Proceeds of such sale or issuance.

(e)                                   Upon the receipt by the Borrower or any of its Subsidiaries of any funds held in an escrow or similar arrangement in connection with, or pursuant to any document related to, any Acquisition (“ Escrowed Funds ”), the Borrower shall prepay an aggregate principal amount of Loans equal to 100% of the amount of such Escrowed Funds.”

(f)                                    Section 6.01(d)  of the Credit Agreement is amended by replacing such Section in its entirety with the following:

“(d)                            as soon as available, but in any event within 30 days after the end of each month, an accounts receivable aging report and accounts payable aging report for the Borrower and each Subsidiary;”

(g)                                 Section 6.02(a)  of the Credit Agreement is amended by replacing such Section in its entirety with the following:

“(a)                             beginning with such financial statements for the fiscal year of the Borrower ending December 31, 2008, concurrently with the delivery of the financial statements referred to in Section 6.01(a)  a certificate of the Registered Public Accounting Firm certifying such financial statements and stating that in making the examination necessary therefor no knowledge was obtained of any Default under any financial covenant contained in this Agreement or, if any such Default shall exist, stating the nature and status of such event;”

(h)                                 Section 6.02(b)  of the Credit Agreement is amended by replacing such Section in its entirety with the following:

“(b)                            concurrently with the delivery of (i) the financial statements referred to in Sections 6.01(a)  and (b) , a duly completed Compliance Certificate in the form attached hereto as Exhibit D-1 and (ii) the reports re