Yeah, that doodoo card's got to go. If a game requires higher then DirectX7, a Voodoo card will likely have issues with it. They were great in their time, but that was a long time ago in the lifespan of video cards. You can nab a GF3/GF4 or Radeon 9000 pretty cheap these days and it would give it a nice shot in the arm. That P3 is a decent CPU, but it is dated. You would probably want to look into a really good H/S and fan so you could push the clock up a bit. More memory is a must--push for 512MB so it has something to work with to compensate for the CPU bottleneck. In the end, you're likely to sink an axtra $200 in it over the next year just to keep things really playable on it.
I think you would be better off buying a barebones 1.5GHz or higher for the same or less. That box would be best for a casual home user that wants to browse the web, maybe play some cheesy games and do a little CD ripping. Not exactly a gamer's machine for what's on the market now, and surely not a good candidate for running emulators on. Even some MAME rom's could have issues with that setup.
If it ain't broke don't try to fix it! But, hell if you can tweak that bastard just a little bit more....hehehe.