Investor Inquiries Cindy Klimstra Director, Investor Relations 847-968-0268 cklimstra@cdw.com   CDW to Webcast 2005 Analyst Day Investor Event VERNON HILLS, Ill - October 27, 2005 - CDW Corporation (NASDAQ: CDWC) today announced that members of its senior management will present at the Company's 2005 Analyst Day investor event at their Mettawa, Ill., office on Wednesday, November 9, 2005. The event will be webcast live at http://www.cdw.com/investor beginning at 9:00 a.m. ET / 8:00 a.m. CT and concluding at approximately 1:15 p.m. ET / 12:15 p.m. CT. The webcast will be available for replay for approximately three weeks. Factors affecting the Company's business and prospects are discussed in the Company's most recent press releases and filings with the Securities and Exchange Commission. Individuals who listen to the webcast will be presumed to have read these documents. Event date and time are subject to change and are based upon current expectations. About CDW CDW® (NASDAQ: CDWC), ranked No. 347 on the FORTUNE 500, is a leading provider of technology products and services for business, government and education. CDW is a principal source of technology from top name brands such as Adobe, APC, Apple, Cisco, HP, IBM, Lenovo, Microsoft, Sony, Symantec, Toshiba and ViewSonic. CDW was founded in 1984 and today employs approximately 4,100 coworkers. In 2004, the company generated sales of $5.7 billion. CDW's direct model offers one-on-one relationships with knowledgeable account managers; purchasing by telephone, fax, the company's award-winning CDW.com Web site, customized CDW@work™ extranets, CDWG.com Web site and macwarehouse.com Web site; custom configured solutions and same day shipping; and pre- and post-sales technical support, with approximately 120 factory-trained and A+ certified technicians on staff. 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.