but my motherboard can support alot of recent CPU's.
And im willing to spend maybe $300 on an upgrade.
Ummm hate to tell you this but the P4 is not even close to recent nor was it a very good gaming chip even when it was new. You have a 1st generation LGA 775 board that supports DDR memory and the P4 5xx and 6xx series. Also the 7600gs was weak even when it was new.
Wait untill you have more to spend and build something that will last. Dont throw away money trying to upgrade this system.
You need a new motherboard, CPU , RAM , Graphics card , Power supply and Hard drive. I really wouldnt even try to salvage any parts off that old thing if you really want a gaming system.
With a few hundred more dollars you can build a core2 or AMD based system that will smoke what you have now.