Gaming pc please read all the details?

[Jon C.]

OK I'm buying/building a gaming computer and i already have a powersupply(650W ULTRA got it last week) an antec 300 case, windows, gaming mouse/keyboard/headset. HDD. List the best builds you can possibly get with this amount and all the components(except the few i mentioned) I'm getting into gaming a little and i want a fast responsive system. I'm NOT talking 60 fps on crysis. However, i still want a somewhat fast, responsive, high FPS system. THANK YOU for your time and effort into getting the components for this system