download 3dmarks 2000 v1.1 from madonion.com
run the default benchmark
post scores...
usually 3500-5500 for Radeons
usually 8000-10000 for GF2 Ultras
usually 5000+ for GF2 MX
etc
it mostly depends on the video card, but if you have a large disparity (i.e. a GF2 ultra on a Pentium 166), the CPU might slow you down, and conversely a 4MB video Card on athlon 1.2Gig isn't the smartest idea either
.
However, anything above 500Mhz for CPU pretty much means you processor is fast enough, the rest is up to the VideoCard
g'luck, let us know the scores