Investor Inquiries Cindy Klimstra Vice President, Investor Relations (847) 968-0268 Media Inquiries Gary Ross Sr. Manager, Corporate Communications (847) 371-5048 CDW's Average Daily Sales Increase 25.8 Percent in May 2007 VERNON HILLS, Ill. - June 11, 2007 - CDW Corporation (NASDAQ: CDWC), a leading provider of technology products and services to business, government and education, today announced average daily sales for May 2007 were $31.520 million, an increase of 25.8 percent compared to average daily sales of $25.057 million for May 2006. Total sales for May 2007 were $693.4 million, an increase of 25.8 percent compared to total sales of $551.3 million for May 2006. Both May 2007 and May 2006 had 22 billing days. As previously announced, CDW completed the acquisition of Berbee Information Networks Corporation on October 11, 2006. May 2006 sales do not include Berbee sales, while May 2007 sales include Berbee sales. Excluding Berbee sales in May 2007, and therefore on a non-GAAP basis, CDW’s average daily sales for May 2007 were $28.990 million, an increase of 15.7 percent compared to average daily sales for May 2006 of $25.057 million and total sales for May 2007 were $637.8 million, an increase of 15.7 percent compared to total sales of $551.3 million for May 2006. In May 2007, average daily sales for the corporate sector segment increased 10.5 percent and average daily sales for the public sector segment increased 26.9 percent compared to the prior year period. While CDW did not own Berbee prior to October 11, 2006, the Company is providing comparative information for Berbee. Compared to the prior year period, average daily sales for Berbee increased 64.5 percent in May 2007. Compared to the public sector and corporate sector segments, Berbee’s business model is more project oriented, which can result in a greater degree of variability in sales on a monthly basis. Product categories that achieved the strongest year-over-year unit volume growth for the month on an average daily basis included notebook computers, desktop computers, data storage, video and input devices. Product categories exclude Berbee sales. The Company plans to announce June 2007 sales on Thursday, July 12, 2007, and second quarter of 2007 earnings on Tuesday, July 24, 2007. June 2006 had 22 billing days and June 2007 will have 21 billing days. About CDW CDW®, ranked No. 342 on the FORTUNE 500, is a leading provider of technology solutions for business, government and education. CDW is a principal source of technology products and services including top name brands such as Acer, Adobe, APC, Apple, Cisco, Fujitsu, HP, IBM, Lenovo, Microsoft, Panasonic, Quantum, Samsung, Sony, Symantec and ViewSonic. CDW's direct model offers customers one-on-one relationships with knowledgeable account managers and access to approximately 820 on-staff engineers and advanced technology specialists who customize solutions for customers’ complex technology needs. CDW also provides same-day product shipping and post-sales technical support. CDW was founded in 1984 and as of March 31, 2007, employed approximately 5,640 coworkers. In 2006, the company generated sales of $6.8 billion. For more information, visit CDW.com. CDW Corporation will file with the Securities and Exchange Commission (the "SEC"), and furnish to its shareholders, a proxy statement soliciting proxies for the meeting of its shareholders to be called with respect to the proposed merger between CDW and Madison Dearborn Partners, LLC. CDW SHAREHOLDERS ARE ADVISED TO READ THE PROXY STATEMENT WHEN IT IS FINALIZED AND DISTRIBUTED TO THEM BECAUSE IT WILL CONTAIN IMPORTANT INFORMATION. CDW shareholders and other interested parties will be able to obtain, without charge, a copy of the proxy statement (when available) and other relevant documents filed with the SEC from the SEC's website at http://www.sec.gov. CDW shareholders and other interested parties will also be able to obtain, without charge, a copy of the proxy statement (when available) and other relevant documents by directing a request by mail or telephone to CDW Corporation, 200 N. Milwaukee Ave., Vernon Hills, Illinois 60061, Attention: Corporate Secretary, telephone: (847) 465-6000, or from CDW's website, http://www.cdw.com. CDW and certain of its directors, executive officers and other members of management and employees may, under SEC rules, be deemed to be "participants" in the solicitation of proxies from shareholders of CDW with respect to the proposed merger. Information regarding the persons who may be considered "participants" in the solicitation of proxies will be set forth in CDW's proxy statement relating to the proposed merger when it is filed with the SEC. Information regarding certain of these persons and their beneficial ownership of CDW common stock as of March 31, 2007 is also set forth in CDW's proxy statement for its 2007 Annual Meeting of Shareholders, which was filed with the SEC on April 16, 2007. Statements about the expected timing, completion and effects of the proposed merger between CDW and Madison Dearborn Partners, LLC, and all other statements in this filing other than historical facts, constitute forward-looking statements within the meaning of the safe harbor provisions of the Private Securities Litigation Reform Act of 1995. Readers are cautioned not to place undue reliance on these forward-looking statements, each of which is qualified in its entirety by reference to the following cautionary statements. Forward-looking statements speak only as of the date hereof and are based on current expectations and involve a number of assumptions, risks and uncertainties that could cause actual results to differ materially from those projected in the forward-looking statements. CDW may not be able to complete the proposed merger because of a number of factors, including, among other things, the failure to obtain shareholder approval, the failure of financing or the failure to satisfy other closing conditions. Other risks and uncertainties that may affect forward-looking statements are described in the reports filed by CDW with the SEC under the Securities Exchange Act of 1934, as amended, including without limitation CDW's Annual Report on Form 10-K for the year ended December 31, 2006. For more information about CDW: Visit CDW on the Internet at http://www.cdw.com. Contact CDW Investor Relations via the Internet at investorrelations@cdw.com or by telephone at 847-419-6328. 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