Graphics card suggestion

Monitor size ?
Games to play ?
A HD4830 is in your price range and would work well at decent res and settings up to about a 22" screen.
Mactronix
Oh almost forgot whats your PSU like ?

HD4830 or 9800gt, both a good match for that cpu at decent resolutions.

Res- 1440 by 900
PSU- 160 w
If it matters, I was only going to play Halflife and Portal.

Sorry about that. Will my PSU be a problem?

4830 will be the best GPU for the games you play

Cant run much on a 160w PSU. Sure you typed that right?

Yes. It's just the default. Can it support the 4830?