I've shot with the Nikon D60, D100, D300, and the Canon Rebel XT, XTi, 20D, 30D, 40D, 5DmkII, and while I think the image quality is more or less equal (especially considering photoshop), I think the canon cameras are arranged in a much more intuitive way in which you are less reliant on the screen to get the shot you want. As far as the technical aspects of photography goes (setting exposure, white balance, ect) both nikon and canon physically work in the same way, it's just the way you enable these settings on the camera that is different. I think the rebel's are great cameras to learn on. They're dirt cheap and take great photos. I'd recommend picking up a Rebel XTi with the stock lens (18-55) plus a 50mm f/1.8, It's a cheap setup that will be great for learning.