THIRD SENIOR EXCHANGE NOTE SUPPLEMENTAL INDENTURE

Exhibit 4.1

THIRD SENIOR EXCHANGE NOTE SUPPLEMENTAL INDENTURE

THIRD SENIOR EXCHANGE NOTE SUPPLEMENTAL INDENTURE, dated as of March 7, 2011 (this “Third Supplemental Indenture”), among CDW LLC, an Illinois limited liability company (“CDW”), CDW Finance Corporation, a Delaware corporation (“CDW Finance” and together with CDW, the “Issuers”), CDW Corporation, CDW Technologies, Inc., CDW Direct, LLC, CDW Government LLC and CDW Logistics, Inc. (together, the “Guarantors”) and U.S. Bank National Association, as trustee (the “Trustee”).

WHEREAS, there has heretofore been executed and delivered to the Trustee an Indenture dated as of October 10, 2008, as amended by the Senior Exchange Note Supplemental Indenture dated as of May 10, 2010 and the Second Senior Exchange Note Supplemental Indenture dated as of August 23, 2010 (as so amended, the “Indenture”), providing for the issuance of the Issuers’ Senior Exchange Notes and Senior PIK Election Exchange Notes (collectively, the “Notes”);

WHEREAS, Section 9.02 of the Indenture provides that the Issuers, the Guarantors and the Trustee may amend the Indenture with the written consent of the Required Holders and Lenders;

WHEREAS, the Issuers and the Guarantors have duly authorized the execution and delivery of this Third Supplemental Indenture;

WHEREAS, the Issuers have offered to purchase any and all of the outstanding Notes for cash (the “Tender Offer”), upon the terms and subject to the conditions set forth in the Issuers’ offer to purchase and consent solicitation statement, dated as of February 22, 2011 (the “Offer to Purchase”), as may be amended, supplemented or modified from time to time;

WHEREAS, in connection with the Tender Offer, the Issuers have also solicited consents from the Holders of the Notes to certain proposed amendments (the “Proposed Amendments”) to the Indenture as described in the Offer to Purchase and set forth in Article I of this Third Supplemental Indenture, with the operation of such Proposed Amendments being subject to the satisfaction or waiver by the Issuers of the conditions to the Tender Offer and the acceptance by the Issuers for purchase and payment of the Notes validly tendered and not validly withdrawn pursuant to the Tender Offer;

WHEREAS, the Required Holders and Lenders have consented to the amendments effected by this Third Supplemental Indenture in accordance with Section 9.02 of the Indenture;

WHEREAS, all things necessary to make this Third Supplemental Indenture a valid agreement, in accordance with its terms, have been complied with or have been performed or done; and

WHEREAS, pursuant to the terms of the Tender Offer to which this Third Supplemental Indenture relates, a consent payment will be made to certain Holders of the Notes who tender their Notes and deliver their consents to the Proposed Amendments.

NOW THEREFORE, in consideration of the foregoing and for other good and valuable consideration, the receipt of which is hereby acknowledged, the Issuers, the Guarantors and the Trustee mutually covenant and agree for the equal and ratable benefit of the Holders of the Notes as follows:

ARTICLE I

AMENDMENTS TO INDENTURE

ARTICLE II

MISCELLANEOUS

[Signature Pages Follow]

IN WITNESS WHEREOF, the parties hereto have caused this Third Supplemental Indenture to be duly executed, all as of the date first written above.

Signature Page to Third Supplemental Indenture

Signature Page to Third Supplemental Indenture