Obligatory blind recommendation for the 3Dfx Voodoo 3.

Ok, so 1 for 3dfx VD3. Anyone else care to weigh in? I know those aren't cheap these days. I'm hoping perhaps for something a little less popular that's still great for the era.

I've paired up a GF3 Ti500 and 9800XT (AGP 8X, currently installed) with the same motherboard that you have, and had no problems.

Yeah, I would say the Voodoo 3 would probably the best choice. As for a cheap choice, Geforce 2 MX should work well. However, I would still recommend to get either a Voodoo 1 or 2 anyway for compatibility reasons.

Anything significantly faster is rather pointless outside of "because I can".

If you just want something cheap that will run the games that a 667Mhz CPU will run, I'd recommend getting something like a Geforce 4 MX 440 or 460. Or maybe an FX 5200. They're a dime a dozen and very compatible. A Voodoo 3 is also a good option for late 90s games, but will cost you a lot more unless you stumble across one that isn't advertised well. A Geforce 4 MX or FX 5200 will also allow much higher resolutions and frame rates in later games. Still, if you're mainly playing late 90s games or games with Glide support and don't mind using lower resolutions (800x600, 1024x768), there's a certain cool factor that comes with running a 3dfx card, if you care about that kind of thing (nostalgia).

If that's an Intel i815 board, you can probably get a much faster CPU to give it some more leg room for games from 2000-2002 or so. If you're expecting to play games from up to 2003, get the Ti 4200 and upgrade the CPU to a 1Ghz or better Pentium III.