The viper v330 would be an excellent choice for what you have for a system. The d3d visual quality is not the greatest, but it is one of the fastest in d3d you could get for your system. 2d speed is also good. A buddy of mine uses this card and is quite happy with it. Another bonus is that these cards are really cheap righ now!
I was running one up until two weeks ago when I bought my Riva TnT. The Viper is a very fast card. The quality is not as bad as people like to say. I bought an 80486 heatsink/fan combo to put on top of it, and upped the memory clock and core clock, which really increased it, with it being no less stable. Worth the 8.00 the fan costs. And, use Nvidias, reference drivers. THe are actually beter than most of the companies final 128 drivers. I've even seen the STB Velocity 128ZX( 8MB version, for as little as 65.00)
I have 200mmx and diamond viper v330 and think its great. Its fast and looks better than you've been led to believe.
I just upgraded to DirectX-6 and upgraded to latest verion of Quake2 and I saw a big increase in Video detail. It looked so good I am having to play it again !