As much as I wanted the range of the 24-105 when I traded in my 17-85 I opted for the 24-70 for the 2.8 apeteure. The 2.8 is nice since the 20d uses the more accurate focusing setting with 2.8 and faster lenses, I learned that trick with the 50 and 24 1.4 I have. I also spend enough time with a tripod and long exposures that the I.s. has only really come in as an advantage with my 300 mm f4 since thats used mainly on sunny days hand held shooting rodeo, surfing, and things that dicatate losing the tripod. The times i am walking around the extra weight of the 24-70 does kind of wear on the neck and it does attract attention with the hood attached.
EOS 20D, EOS 5-D MK2, 50 MM 1.4, 24-70 MM 2.8 L, 17-40 M.M. F4 L, 70-200 F4L, 300 F4 L IS, 580 EX, 430 EX, Hensel Integra Pro Plus 500 W.S. X 3, ST-E2 Transmitter, BG-E2 Grip, Epson R1800 Printer and a credit card that has a nervous twitch