I game, I currently have a 4850 512 mb I want to get a 480 and water cool with the rest of my rig

But I only have a 650 PS? Might go with a 5870 but driver issues makes me not want to.

High FPS would be nice,
I have a 24 inch Monitor 1920

I just wanted to know if a OC E8500 to a I7 would be night and day difference?