I have the Canon Rebel XT too and love it. I have taken some amazing pictures and still do not understand all of the exposure settings. Thankfully the auto settings do a pretty good job. My only disappointment is night action shots. I need a faster lens to stop the blur or need to learn the art of panning. I bought mine mostly for son's sports too and although the baseball pictures are great, my football shots less so, and basketball -- well even the pros complain about those weird gym lights.
I would stick with Canon lenses. I strayed once to a Quantaray for my telephoto and am not happy with it. My favorite lens is the little 50 mm 1.8 -- takes such clear shots you want to reach out and touch them.
I have not braved raw photos yet either although my reading is telling me I need to learn. I think I have a point & shoot mind.
