Have you been having any of the "commonly reported" 20D focusing issues? (front/rear focusing etc)?
I just picked up a 20D and a few lenses (Canon EF 50mm f/2.5 macro, Canon EF L 200mm f/2.8, Tokina ATX 300mm f/4). I notice some hesitation and searching with the Tokina (it's noisey also). It has a difficult time locking onto flying birds etc. It's tack sharp when it's AF lock onto something. I'm still tinkering with the camera but seem to have one that focuses "normally". I can't wait to head back to the Florida aquarium. :-D