S3 ViRGE! Why? Performance/Price=Infinite!
Ok, performance aint so hot. Maybe 3 seconds per frame in Wolfenstein 3D. But I'm sure you can find thousands of people who would give you one for free, so price=0. That makes for one great performance/price ratio!
Seriously tho, go get you a new processor, then you will actually get some benefits from a new videocard.