Well, I have a PII 333 with 96 mb SDRam and a Voodoo3 3000. It screams and hasn't let me down yet. I had the Viper V770 on preorder, but got sick of waiting. You really have to do some research on your own and form your own opinion. There are pro's and con's for either choice. TNT2 is clocked slower than the Voodoo3s, but comes with O/C utilities. The TNT2 will support 32-bit color, but the TNT2 doesn't have Glide. Little things like that could make a difference to some people, but might not bother you at all. DiamondMM.com and 3dfx.com, check them out.
No, really, it's just a chemical imbalance.