Well you could think about getting a GF4Ti4200 or 4800 those are pretty good when you consider the price of them, they should also have Pixel Shader. The FX5xxx series is a disgrace.
as far as i know, the 128mb version is slightly better. (but the difference is that small, its not worth replacing a 64Mb card with a 128mb one, then you could better buy a better one )
Well I got one, and I wanted to know which one was better, becuase iu was going to oput that in this machine, then the other was going to replace a 16MB video card.