**LIBOR Monthly**        **Floating Rate+****Pricing Level** **Consolidated Leverage Ratio** **Unused Fee** **L/C Fee**1 Less than or equal to 1.00 to 1.00  0.150%  2.000%           2 Less than or equal to 1.50 to1.00, but greater than 1.00 to1.00  0.200%  2.250%           3 Less than or equal to 2.00 to1.00, but greater than 1.50 to1.00  0.250%  2.500%           4 Greater than 2.00 to 1.00  0.250%  2.750% (ii) A new definition of “Disposition of Screening” is added thereto inits appropriate alphabetical order to read as follows:   “Disposition of Screening” means (i) a Disposition by a Loan Partyor Subsidiary of any Equity Interests of SI Holdco or the ABI Loan, (ii) aDisposition of all or substantially all of the assets of SI Holdco, or (iii)a Disposition of all or substantially all of the assets of SI. (iii) A new definition of “Net Cash Proceeds” is added thereto in itsappropriate alphabetical order to read as follows:   “Net Cash Proceeds” means (a) with respect to any Disposition by anyLoan Party or any of its Subsidiaries, or any insurance or condemnation awardreceived or paid to the account of any Loan Party or any of its Subsidiaries, theexcess, if any, of (i) the sum of cash and cash equivalents received in connectionwith such transaction (including any cash or cash equivalents received by way ofdeferred payment pursuant to, or by monetization of, a note receivable or otherwise,but only as and when so received) over (ii) the sum of (A) the principal amount ofany Indebtedness that is secured by the applicable asset and that is required to berepaid in connection with such transaction and any Indebtedness that is owed by anySubsidiary being Disposed of and required to be prepaid in connection with suchtransaction (in either case, other than Indebtedness under the Loan Documents), (B)the reasonable and customary out-of-pocket expenses incurred by such Loan Party orsuch Subsidiary in connection with such transaction, (C) income taxes reasonablyestimated to be actually payable within two years of the date of the relevanttransaction as a result of any gain recognized in connection therewith;provided that, if the amount of any estimated taxes pursuant to subclause(C) exceeds the amount of taxes actually required to be paid in cash in respect ofsuch Disposition, the aggregate amount of such excess shall constitute Net CashProceeds, and (D) any management fees or other amounts due in the ordinary course ofbusiness to the Loan Party making the Disposition by the entity being Disposed of,to the extent paid as a part of such Disposition; and (b) with respect to the saleor issuance of any Equity Interest by any Loan Party or
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   any of its Subsidiaries, or the incurrence or issuance of any Indebtedness(other than Indebtedness under the Loan Documents) by any Loan Party or any of itsSubsidiaries, the excess of (i) the sum of the cash and cash equivalents received inconnection with such transaction over (ii) the underwriting discounts andcommissions, and other reasonable and customary out-of-pocket expenses, incurred bysuch Loan Party or such Subsidiary in connection therewith. (b) Section 2.05(d) is amended by adding new clause (iii) to such Section andrenumbering existing clause (iii) as new clause (iv), and replacing the references to clause“(iii)” in clauses (i) and (ii) thereof to clause “(iv)”; new clause (iii) shall read asfollows:   “(iii) Within five Business Days of any Disposition permitted by Section7.05(f), the Borrowers shall prepay an aggregate principal amount of Loans inthe amount set forth in such Section (such prepayment to be applied as set forth inclause (iv) below).” (c) Section 7.02(h) of the Credit Agreement is amended by replacing the amountof $5,000,000 therein with the amount of $6,500,000. (d) Section 7.05 is amended by replacing such Section in its entirety with thefollowing: **7.05** **Dispositions**. Make any Disposition or enter into any agreement to makeany Disposition, except: (a) Dispositions of obsolete or worn out property, whethernow owned or hereafter acquired, in the ordinary course of business; (b) Dispositions of inventory in the ordinary course ofbusiness; (c) Dispositions of equipment or real property to theextent that (i) such property is exchanged for credit against the purchaseprice of similar replacement property or (ii) the proceeds of suchDisposition are reasonably promptly applied to the purchase price of suchreplacement property, and in each case, such purchase of replacementproperty is promptly consummated; (d) Dispositions of property by any Subsidiary to aBorrower or to a Guarantor; (e) Dispositions permitted by Section 7.04; (f) A Disposition of Screening, provided that 50% of theNet Cash Proceeds of such Disposition are applied to prepay Loans inaccordance with Section 2.05(d)(iii);
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 (g) Dispositions resulting from casualty loss orcondemnation; and (h) Dispositions permitted by Section 7.02;   provided, however, that any Disposition pursuant to clauses (a)through (e) above shall be for fair market value or consideration otherwisereasonably satisfactory to the Administrative Agent.     2. Effectiveness; Conditions Precedent. This Agreement and the amendments to theCredit Agreement herein provided shall become effective upon satisfaction of the followingconditions precedent: (a) the Administrative Agent shall have received each of the following documents orinstruments in form and substance reasonably acceptable to the Administrative Agent: (i) counterparts of this Agreement, duly executed by the Borrowers, theAdministrative Agent and the Lenders, together with all schedules and exhibitsthereto duly completed; (ii) such other documents, instruments, opinions, certifications, undertakings,further assurances and other matters as the such other assurances, certificates,documents, consents or opinions as the Administrative Agent, the L/C Issuer, or theLenders may reasonably require; (b) the Fourth Amendment Fee (defined below) and all other fees and expenses payable tothe Administrative Agent and the Lenders (including the fees and expenses of counsel to theAdministrative Agent) estimated to date shall have been paid in full (without prejudice tofinal settling of accounts for such fees and expenses).     3. Amendment Fee. The Borrowers shall pay to the Administrative Agent, for theaccount of each Lender, a fee (the “Fourth Amendment Fee”) in an amount equal to 0.10%multiplied by the sum of (i) the aggregate outstanding principal amount of the Term Loan held bysuch Lender, plus (ii) such Lender’s Revolving Credit Commitment. Each Fourth AmendmentFee shall be for such Lender’s execution of this Agreement, shall be fully earned on the datehereof, shall be due and payable on the date hereof, and shall be non-refundable for any reasonwhatsoever.     4. Representations and Warranties. In order to induce the Administrative Agent andthe Lenders to enter into this Agreement, the Borrower represents and warrants to theAdministrative Agent and the Lenders as follows: (a) The representations and warranties made by each Loan Party in Article V ofthe Credit Agreement and in each of the other Loan Documents to which such Loan Party is aparty are true and correct on and as of the date hereof, except to the extent that suchrepresentations and warranties expressly relate to an earlier date;
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 (b) Since the date of the most recent financial reports of the Company and itsSubsidiaries delivered pursuant to Section 6.01 of the Credit Agreement, no act,event, condition or circumstance has occurred or arisen which, singly or in the aggregatewith one or more other acts, events, occurrences or conditions (whenever occurring orarising), has had or could reasonably be expected to have a Material Adverse Effect; (c) The Persons constituting Borrowers after giving effect to the effectiveness hereof(and assuming satisfaction of the conditions subsequent set forth in Section 3 ofthis Agreement) are all Persons required to be Designated Co-Borrowers under Section6.13 of the Credit Agreement. (d) This Agreement has been duly authorized, executed and delivered by the Borrowersand constitutes a legal, valid and binding obligation of such parties, except as may belimited by general principles of equity or by the effect of any applicable bankruptcy,insolvency, reorganization, moratorium or similar law affecting creditors’ rights generally; (e) After giving effect to this Agreement, no Default or Event of Default has occurredand is continuing.     5. Entire Agreement. This Agreement, together with all the Loan Documents, thatcertain consent and waiver letter dated August 25, 2006 from Bank of America, N.A., asLender, to the Company, and that certain consent letter dated November 2, 2007 from Bank ofAmerica, N.A., as Lender, to the Company (collectively, the “***Relevant Documents***”), sets forth theentire understanding and agreement of the parties hereto in relation to the subject matter hereofand supersedes any prior negotiations and agreements among the parties relating to such subjectmatter. No promise, condition, representation or warranty, express or implied, not set forth inthe Relevant Documents shall bind any party hereto, and no such party has relied on any suchpromise, condition, representation or warranty. Each of the parties hereto acknowledges that,except as otherwise expressly stated in the Relevant Documents, no representations, warranties orcommitments, express or implied, have been made by any party to the other in relation to thesubject matter hereof or thereof. None of the terms or conditions of this Agreement may bechanged, modified, waived or canceled orally or otherwise, except in writing and in accordance withSection 10.01 of the Credit Agreement.     6. Full Force and Effect of Agreement. Except as hereby specifically amended,modified or supplemented, the Credit Agreement and all other Loan Documents are hereby confirmedand ratified in all respects and shall be and remain in full force and effect according to theirrespective terms, as modified by (i) that certain consent and waiver letter dated August 25, 2006 from Bank of America, N.A., as Lender, to the Company and (ii) that certain consentletter dated November 2, 2007 from Bank of America, N.A., as Lender, to the Company.     7. Counterparts. This Agreement may be executed in any number of counterparts, eachof which shall be deemed an original as against any party whose signature appears thereon, and allof which shall together constitute one and the same instrument.
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     8. Governing Law. This Agreement shall in all respects be governed by, and construedin accordance with, the laws of the Commonwealth of Virginia applicable to contracts executed andto be performed entirely within such Commonwealth, and shall be further subject to the provisionsof Section 10.13 of the Credit Agreement.     9. Enforceability. Should any one or more of the provisions of this Agreement bedetermined to be illegal or unenforceable as to one or more of the parties hereto, all otherprovisions nevertheless shall remain effective and binding on the parties hereto.     10. References. All references in any of the Loan Documents to the “Credit Agreement”shall mean the Credit Agreement, as amended hereby.     11. Successors and Assigns. This Agreement shall be binding upon and inure to thebenefit of the Borrowers, the Administrative Agent and each of the Lenders, and their respectivesuccessors, legal representatives, and assignees to the extent such assignees are permittedassignees as provided in Section 10.06 of the Credit Agreement.*[Signature pages follow.]*
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     **IN WITNESS WHEREOF**, the parties hereto have caused this instrument to be made, executed anddelivered by their duly authorized officers as of the day and year first above written.      **BORROWERS****:**