It will really depend on the light. If it's bright, then the lens should be OK...but if the light is not very bright...you will have a hard time getting a shutter speed that is fast enough to freeze the action.
The 20D performs well at high ISO...so if you don't mind some digital noise, you can crank the ISO up to 800, 1600 or (H) 3200 to help freeze the action.
IS is nice, because it helps to eliminate camera shake when shooting hand held...however, it will not help to reduce blur from subject movement...only a fast shutter (or flash) can do that. The IS would be helpful for getting a clearer shot when the action is not so fast though. Some IS lenses have a 'Pan' mode...which is to be used while on a tripod or mono-pod. This might help but I don't know if this lens has that option. Essentially, IS is not a substitute for a wider aperture when it comes to sports.
If you can afford a faster lens, that would be ideal. The 70-200 F2.8 is well renowned but it's heavy and expensive. Sigma makes one that is cheaper and almost as good. There is also an F4 version of the 70-200, which is a good lens but not much faster than 4.5-5.6