Hi, i got alot of good responses a while back when I posted about buying a Digital SLR, so I figured I'd come back here now that i'm ready to buy a new lens. I would like to start with a good quality zoom lens, probably a 70-200mm, but i'm not sure if I should go for an f/4 or f/2.8 model. The Canon 70-200 f/4 is $550 at B&H, which is pretty decent for an "L" lens I would think. However, I do alot of shooting indoors, so the f/2.8 would be a much better idea. Since both f/2.8 70-200 models from canon are over $1,000 and out of my budget, I found myself looking at the Sigma 70-200 f/2.8 EX The sigma seems to have very good reviews. I'm still a little bit wary of buying non-Canon lenses, but if the price is right and its good glass, I may go for it. My other concern was the size and weight of these lenses. The Rebel XT is a small camera... will it be awkward using a lens this large on such a small camera? Will it be manageable when used handheld, or would I have to use it on a tripod all the time? I'd appreciate it if some of the pros here could give me some advice on the lenses in this range. Thanks!