It's a tough call. And really, I think it's more important to consider the camera and system you're buying into. With this kind of purchase, shopping by price can be a big mistake. Different people have very definite preferences about which SLR they like better. And it's as much a question of how the camera fits as anything else. Both cameras will be perfectly adequate as far as specs go, although a faster frame rate might help. On the other hand, the 18-135mm lens that comes with the Nikon has a lot mroe to offer as an all-purpose lens. The 28mm wide end of the Canon 28-135mm IS lens isn't really a wide angle lens with the 30D's 1.6x crop.

Personally, I would recommend looking at the Canon Digital Rebel XTi and the Nikon D40x to see if they'll do the job. I don't think you really need more than they have to offer. And with the money you save on the "entry-level" body, you can buy better lenses and a real flash. If you're shooting indoor sports, a good flash is invaluable. Lot's of people disagree with me about the Digital Rebel XTi. But I've shot with the best equipment available and my main camera right now is the XTi, and most of what I shoot is sports. Hardly anyone needs to shoot 5 frames-per-second. A better lens will deliver more, for most people.