Hi, I'm thinking of upgrading my pc. i've got an lga775 p5g41t motherboard. it supports core 2 duo and quad core processor. currently i'm running on pentium 4 630 64bit processor. I usually use it for gaming. I'm thinking of playing farcry 2, assassin's creed, dragon age 2, gta 4 etc. Which processor should i buy? Currently i'm on onboard graphics with shader model 4.0. Can i play above listed games without upgrading my processor and only by adding an extra graphic card? (That way i can save some money.)