From looking around on the internet I have noticed that some places will sale the canon 20d in a kit that comes with a 18-55 mm lens. Some of these kit lenses say they are USM and some say they are not. In fact on Adorama website, there is a 40 dollar difference between the two.
What actually is the difference between the usm and non usm lenses? Are either of them any good? I know I have heard a lot of praise for the 17-85mm lens. Just wondering if I go the kit lens route if I should find one that has a usm lens.
Thanks for the help
Jason