Really? I have Radeon 5770s in CF - so 2GB theoretical VRAM - and an i5 750 (2.66GHz quad core, I run it at 3.04) backed up by 4GB system memory and Race 07 maxed out
still manages to bring my system to its knees on occasion. It easily runs at 100+ fps when I'm the only car but chuck in some AI and the framerate takes a nosedive - I've seen 15-20fps with a train of AI vehicles in front of me

rFactor is just as bad, 150+fps solo but add in more cars and that drops to around a third. My performance in S2U is a lot better than what you get though, easy 40+ @ 1920x1080