The motherboard says it Supports Intel® Core™2 Extreme Quad-Core. I'm assuming that doesn't include the Core 2 Quad 9xxx series. Which means the highest I could upgrade without buying a new motherboard and without spending too much money is what, the Core 2 Duo E8500? Would I be better off buying a new motherboard/CPU such as the i5 750 (Off topic but what motherboards would you recommend? I never plan on using xfire and SATA3/USB3 aren't necessary) What kind of performance increase would I see as far as video games go? Is the extra $250 worth it (DDR3 and Mobo) assuming I can spend the money but I don't necessarily want to.
Also, I'm currently using a 9800GT and I'm about to upgrade to an ATI 5850.
If you live near a Micro Center they sell Core 2 Quad Q9550s for $169.99 I believe (if they still stock it) pickup only, which would make a good upgrade. Otherwise I suppose there's not much point pumping too much $ into a dead platform, and you'd be better off with a Core i5 750 system, unless you don't mind waiting for SB.
not as twice as good but ya i5 will outperform Q9xxx Quad with turbo boost and hyper threading ( selected i5 models only )
if u want to save money right now just buy a Q9xxx series Quad because an i series upgrade is costly.