Yeah thats pretty good, running a p4 2.8GHz with Nvidia 6200 256MB, I get about 50-60 in race, when on my own playing or replay type of thing its 70-90 roughly!
Dont know if you can count this, but I have cartilage damage to both of my knees (from lots of hiking, jogging and cycling a few years back, I still do it all at times which does not help!)
But when in a long race, or race after race after race for a few hours my knees really ache! Its painful at times when I stand up again also