I upgraded to an NVIDIA 5500/256MB and enabled bump maps by editing one of the core game files (I don't remember which one). That's when my game slowed down so badly. There's also a boolprop cheat you can enter to acitvate both bump maps and the brighter, more animate pool water, but you get the same slow-down on the lower-end cards.
Properly done bump maps look good. Unfortunately, among the usermade content that I have, there are very
very few properly done bump maps. Contrarty to what some tutorials suggest, it's more than a matter of clicking a couple of filters. I found otherwise beautiful skins suddenly looking like they were embedded several inches into the Sim's body (light and dark backwards on the bump map), or what was supposed to be sheer, filmy fabric appearing two inches thick (too much contrast on the bump map). To me, it's simply not worth the trouble and expense to enable the damn things. GOOD textures don't need them, anyway.