Wes Jordan said:
the Rebel XT is just too whimpy and the 5 FPS compared to 3 FPS is a big difference.
You've chosen the most equipment intensive type of photography, sports at night. There is just no way around the need for big expensive optics. You should have selected studio portraits or landscapes and saved about a kilo-buck.
Look at Nikon. Both Nikon and Canon have very good build quality at the high ends of their lines but Canon goes "realy cheap" at the low end. As you fond out the Rebel feels like a plastic box filled with air. But even the sub $500 Nikon D50 has a very solid feel to it.
But if you can afford the 20D you need to look at Nikon's D200. and also the Canon 30D which has just replaced the 20D. All are about the same price
If cost is an issue look for a good used lens. Lenses are a mature technology and a ten year old one makes as good an image as a new one. Remember it's the LENS that makes the image, the camera body only records it.
One other thing to concider is if you shoot in RAW format you can "push" the exposure up about one stop later in software. Yes it adds noise.
Don't think that using a high continous frame rate will get you the shot. It will get you 8 frames all taken at the "wrong" instant. The trick with sports photography is to capture THE moment, not 18 moments on either side of it. The way the pros do this to, have some "feel" for the subject and at least menally make the jump with the guy makeing that layup and trip the shutter when you and him are weightless at the top of the arc.
Also it should be clear that a flash and fast frame rates don't mix. Flash re-cycle times are on the order of a handfull of seconds unless you have some big bucks to throw at the problem
See if you can't fit at least a monopod into you budget. It will give you about 1/2 f-stop but you'll still need to remember to shoot with shutter speeds at least 1/lens focal lenght. So that's abot 1/200 or faster