It sounds like you could use a digital slr with a fast(lets plenty of light through) lens. Since your subjects will be moving fast a tripod won't help much,
and you will need to use a fast shutter speed, so image stabilization won't help you much either. You need a camera with a low noise iso 1600 or iso 3200 mode, such as a digital slr. The rule of thumb for photography(without image stabilization) is that the shutter speed should be faster than 1/equivalent 35mm film camera focal length. For example, if you use a lens that is 300mm equivalent, then your shutter speed should be 1/500th of a second or faster. Most lenses don't let much light through at such a focal length(perhaps they are f5.6 or slower?) so you would need a high iso setting to take a photo at 1/500th f 5.6 or f8 except in the brightest daylight.A Digital Rebel or 20D with an 80-200mm f2.8 lens(the camera has a 1.6x factor, so at the 200mm setting on the lens it acts like the equivalent of a 320mm lens)
set at up to 1600 ISO would give you plenty of leeway to take the type of photos you want to take. Most non slr digital cameras only go up to 400 iso, and even at 400 ISO the images are very noisy. Those that have an 800 iso mode are extremely noisy at that setting. My advice to you is to buy a digital slr and some nice lenses. Yes, it will be expensive, but it will allow you to take the type of images you want to take. A Digital Rebel is around $800, while a 20D is around $1600. That is just for the camera body. An 80-200mm f2.8 lens might cost around $900 or so. Then there are memory cards and extra batteries. I don't own a digital slr yet, but am considering buying one. I have been studying the issue, and was waiting for the price of the digital Rebel to drop, but now I like the images on the web that I have seen from the 20D. So I am not so in love with the Digital Rebel anymore.