Cheers mate :-)
I used a Canon Eos 400D with Sigma 55 - 200mm lens with a Hoya UV filter. My first time using it for action shots and I'm reasonably happy with the results as the lighting was a nightmare especially towards the end of the day when the light was fading fast. I should also have got off my bum and moved round the circuit a bit for some different shots. My excuse was it was cold and I was stood close to the food/tea vans!
Nick