If $200 USD is your max, you don't mind paying close to the full amount, noise isn't a factor, power isn't a factor, then there is only one choice at the moment :
Factory OC GTX460 1GB $179.99It will give you the best bang for buck of any gfx card on sale today.
The 1GB has a premium over the cheaper $140 768MB version but rightly so as it has a reasonable bandwidth and performance advantage.
