FIRST AMENDMENT TO FIRST AMENDED AND RESTATED

Exhibit 10.43

FIRST AMENDMENT TO FIRST AMENDED AND RESTATED

SECURITY AGREEMENT

THIS FIRST AMENDMENT TO FIRST AMENDED AND RESTATED SECURITY AGREEMENT (herein called this “Amendment”) made as of the 2nd day of April, 2007 by and between U.S. HOME SYSTEMS, INC., a Delaware corporation (“Debtor”), and THE FROST NATIONAL BANK, a national banking association (“Lender”).

W I T N E S S E T H:

WHEREAS, Debtor and Lender have entered into that certain First Amended and Restated Loan Agreement dated as of February 9, 2006, to be effective for all purposes as of February 10, 2006 (as from time to time amended, modified or restated, the “Loan Agreement”) for the purposes and consideration therein expressed, pursuant to which Lender became obligated to make loans to Debtor as therein provided; and

WHEREAS, Debtor and Lender have entered into that certain First Amended and Restated Security Agreement dated as of February 9, 2006, to be effective for all purposes as of February 10, 2006 (as from time to time amended, modified or restated, the “Original Security Agreement”) for the purposes and consideration therein expressed, pursuant to which Debtor pledged and granted to Lender a continuing security interest in Collateral; and

WHEREAS, Debtor and Lender desire to amend the Original Security Agreement for the purposes expressed herein;

NOW, THEREFORE, in consideration of the promises and the mutual covenants and agreements contained herein and in the Original Security Agreement, in consideration of the loans which may hereafter be made by Lender to Debtor, and for other good and valuable consideration, the receipt and sufficiency of which are hereby acknowledged, the parties hereto do hereby agree as follows:

ARTICLE I.

DEFINITIONS AND REFERENCES

§ 1.1 Terms Defined in the Original Agreement. Unless the context otherwise requires or unless otherwise expressly defined herein, the terms defined in the Loan Agreement or the Original Security Agreement shall have the same meanings whenever used in this Amendment.

§ 1.2. Other Defined Terms. Unless the context otherwise requires, the following terms when used in this Amendment shall have the meanings assigned to them in this § 1.2.

“Amendment” means this First Amendment to First Amended and Restated Security Agreement.

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“Security Agreement” means the Original Security Agreement as amended hereby.

ARTICLE II.

AMENDMENTS TO ORIGINAL SECURITY AGREEMENT

§ 2.1. Indebtedness. Section 1(d) of the Original Security Agreement is hereby amended to read:

(d) The term “Indebtedness” shall mean (i) all indebtedness, obligations and liabilities of Obligor to Secured Party of any kind or character, now existing or hereafter arising, whether direct, indirect, related, unrelated, fixed, contingent, liquidated, unliquidated, joint, several or joint and several, and regardless of whether such indebtedness, obligations and liabilities may, prior to their acquisition by Secured Party, be or have been payable to or in favor of a third party and subsequently acquired by Secured Party (it being contemplated that Secured Party may make such acquisitions from third parties), including without limitation all indebtedness, obligations and liabilities of Obligor to Secured Party now existing or hereafter arising by note, draft, acceptance, guaranty, endorsement, letter of credit, assignment, purchase, overdraft, discount, indemnity agreement or otherwise, including, without limitation (a) that one certain Revolving Promissory Note dated as of April 2, 2007, executed by Obligor and payable to the order of Secured Party, in the original principal amount of $6,000,000, which note was executed in renewal and replacement (but not in extinguishment or novation) of (1) that one certain Revolving Promissory Note dated as of February 9, 2006, to be effective as of February 10, 2006, executed by Obligor and payable to the order of Secured Party, in the original principal amount of $3,000,000, and (2) that one certain Revolving Promissory Note dated as of February 9, 2006, to be effective as of February 10, 2006, executed by Obligor and payable to the order of Secured Party, in the original principal amount of $4,000,000, (b) that one certain Term Note dated as of February 9, 2006, to be effective as of February 10, 2006, executed by Obligor and payable to the order of Secured Party, in the original principal amount of $1,200,000, and (c) that one certain Term Note dated as of February 9, 2006, to be effective as of February 10, 2006, executed by Obligor and payable to the order of Secured Party, in the original principal amount of $875,000; (ii) all accrued but unpaid interest on any of the indebtedness described in (i) above, (iii) all obligations of Obligor to Secured Party under any documents evidencing, securing, governing and/or pertaining to all or any part of the indebtedness described in (i) and (ii) above, (iv) all costs and expenses incurred by Secured Party in connection with the collection and administration of all or any part of the indebtedness and obligations described in (i), (ii) and (iii) above or the protection or preservation of, or realization upon, the collateral securing all or any part of such indebtedness and obligations, including without limitation all reasonable attorneys’ fees, and (v) all renewals, extensions, modifications and rearrangements of the indebtedness and obligations described in (i), (ii), (iii) and (iv) above.

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ARTICLE III.

REPRESENTATIONS AND WARRANTIES

§ 3.1. Representations and Warranties of Debtor. In order to induce Lender to enter into this Amendment, Debtor represents and warrants to Lender that:

(a) The representations and warranties contained in Section 4 of the Original Security Agreement are true and correct at and as of the time of the effectiveness hereof.

(b) Debtor is duly authorized to execute and deliver this Amendment. Debtor has duly taken all action necessary to authorize the execution and delivery of this Amendment.

(c) The execution and delivery by Debtor of this Amendment, the performance by Debtor of its obligations hereunder and the consummation of the transactions contemplated hereby do not and will not conflict with any provision of law, statute, rule or regulation or of the articles of incorporation of Debtor, or of any material agreement, judgment, license, order or permit applicable to or binding upon Debtor, or result in the creation of any lien, charge or encumbrance upon any assets or properties of Debtor. Except for those which have been duly obtained, no consent, approval, authorization or order of any court or governmental authority or third party is required in connection with the execution and delivery by Debtor of this Amendment or to consummate the transactions contemplated hereby.

(d) When duly executed and delivered this Amendment will be a legal and binding instrument and agreement of Debtor, enforceable in accordance with its terms, except as limited by bankruptcy, insolvency and similar laws applying to creditors’ rights generally and by principles of equity applying to creditors’ rights generally.

ARTICLE IV.

MISCELLANEOUS

§ 4.1. Ratification of Agreements. The Original Security Agreement as hereby amended is hereby ratified and confirmed in all respects. The execution, delivery and effectiveness of this Amendment shall not, except as expressly provided herein or therein, operate as a waiver of any right, power or remedy of Lender under the Loan Agreement, the Notes, or any other Loan Document nor constitute a waiver of any provision of the Loan Agreement, the Notes or any other Loan Document.

§ 4.2. Survival of Agreements. All representations, warranties, covenants and agreements of Debtor herein shall survive the execution and delivery of this Amendment and the performance hereof.

§ 4.3. Loan Documents. This Amendment is a Loan Document, and all provisions in the Loan Agreement pertaining to Loan Documents apply hereto.

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§ 4.4. Governing Law. This Amendment shall be governed by and construed in accordance with the laws of the State of Texas and any applicable laws of the United States of America in all respects, including construction, validity and performance.

§ 4.5. Counterparts. This Amendment may be separately executed in counterparts and by the different parties hereto in separate counterparts, each of which when so executed shall be deemed to constitute one and the same Amendment.

THIS AMENDMENT AND THE OTHER LOAN DOCUMENTS REPRESENT THE FINAL AGREEMENT BETWEEN THE PARTIES AND MAY NOT BE CONTRADICTED BY EVIDENCE OF PRIOR, CONTEMPORANEOUS, OR SUBSEQUENT ORAL AGREEMENTS OF THE PARTIES. THERE ARE NO UNWRITTEN ORAL AGREEMENTS OF THE PARTIES.

IN WITNESS WHEREOF, this Amendment is executed as of the date first above written.

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