CMR05, F1C ('99-'02 Challenge) will run for sure without any hick-ups
F1C will run at even 1024*760 resolutioin
NFS MW will have usual hickups every now & then one has to wait for 5 minutes when game/race/safe house loads.
RBR will have some FPS issues
(256RAM)
btw RBR is a game i'll not recommend, unless you're a hardcore WRC & Sim. fan & yes you'll need a Steering Wheel to enjoy this game. (gamepad wont be enuf, trust me
)
other soft sim. racers are
NFS Porsche Unleashed (NFS PU), really nice game, imo the BEST NFS title so far.
you can also try
Live For Speed
F1 - ~Rs.500/-
NFS PU - ~Rs.500/-
CMR05 - ~hard to find
RBR - same, hard to find.
NFS MW - ~Rs. 1200