I have a 2100+ @ 2.4GHz and a 9500 Pro a 400/340... no problems at 1280x960 everything full but no AF/AA.
CMR 2005 drives just like CMR 4... except for a few nice graphical tweaks here and there. I've had all the CMR series... I think the car models in CMR 2005 are just awesome though.
You should check out Richard Burns Rally as well... that one has crappy car models (they just started editing it so expect a nicers ones soon) but the driving physics is just nuts. :heart: