Investor Inquiries Cindy Klimstra Director, Investor Relations 847-968-0268 cklimstra@cdw.com Media Inquiries Gary Ross Sr. Manager, Corporate Communications 847-371-5048 garyross@cdw.com CDW to Release Third Quarter Results on October 18, 2005 VERNON HILLS, Ill - October 11, 2005 - CDW Corporation (NASDAQ: CDWC) will release its third quarter 2005 results and September 2005 sales results on Tuesday, October 18, 2005, at 7:30 a.m. ET / 6:30 a.m. CT. Management will review these results during a conference call on Tuesday, October 18, 2005 at 8:30 a.m. ET / 7:30 a.m. CT. This conference call will be available via live webcast in listen-only mode on the Company's web site at CDW.com. An audio replay of the call will be available approximately two hours after the event on CDW.com for approximately two weeks. 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 approximately $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 more than 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.