yeah, my first mame pc was a pentium pro 200. played classics just fine.
then got a pentium 3 in the cab. that played a lot of newer 2d shooter/ fighting games fine
then a pentium 4. that played pretty much the vast majority of the games including some 3d games
now with an oc'd core2duo, a lot of 3d games are playable except some of the higher bar games like gauntlet legends