0000950137-07-008315 DEFA14A 1 20070531 20070531 20070531 CDW CORP 0000899171 5961 363310735 IL 1231 DEFA14A 34 000-21796 07891804 200 N MILWAUKEE AVE VERNON HILLS IL 60061 8474656000 200 N MILWAUKEE AVE VERNON HILLS IL 60061 CDW COMPUTER CENTERS INC 19930322 DEFA14A 1 c15694defa14a.htm SOLICITING MATERIAL