I upgraded my Geforce 4 Ti4200 64MB to a Radeon 9600 Pro 128 MB.
Let me say this, it was WELL worth the money*. The only hard-core** 3D accelerated game that I play is Battlefield 1942. Gawd dam, it made such a difference. I can now turn everything up to full detail and run the game smoothly without any frame drops.
*I paid $173 for mine and now after 2-3 weeks it drops to $133. Dammit I'm pissed. Prices are according to Pricegrabber.com or Newegg.com
**I know, BF1942 isn't the more hardcore card user since there are games such as Unreal 2, Quake 3, etc etc that are the games used for benchmarks.
I did a page
here on my website just to help you guys and gals out if you need to upgrade.