Mark, like eyeayen said, your camera’s ok. Unfortunately there are not many more demanding things to shoot than indoor sports. The dream Canon lens for indoor RCs is the 70-200mm L F2.8 mk2, but that’s almost 2k!
I use a 70-200mm F4 IS L, which is half the price, but I wouldn’t have much hope for it indoors. When it got cloudy at the oople race I had to go uncomfortably high in the iso range.
For experimenting, the cheapest option would be something like Canon's 50mm F1.8 (£80) and try to get in close to the action; it’ll give you more of a feel for what a big aperture lens can do.
Alternatively, if you’ve got an event coming up, rent a lens from someone like lensesforhire.co.uk, I use them quite a bit and they’re very good, lets you really see what lenses are good for what you shoot.