Gaming Computer Help. Need a Real Genius to help here.?

Vista for a lot of people is very problematic, i would recommend going with 7 but if its to pricey stay with vista. As for your pc its a very nice setup for 600 dollars, the only problem is you are going to get very frustrated having a slow mouse and keyboard for gaming, especially if your into shooters or driving games. Also your 9500gt is getting really old very quickly its recommended that you go with a bigger card like a 9800gt which would only cost 30 more dollars much better card, vista supports all games but doesnt use dx9 so you will lag more also a more demanding os so you will experience less fps then someone with your same setup but with 7 or XP, also 320 gb is not very good for gaming and it will soon get very crowded and it will start to freeze up and go very slow, you have excellent ram ddr3 @ 1333 VERY NICE choice also you have a nice quad core cpu, be sure you get 64 BIT AND NOT 32BIT with 32 bit it will only record 3.92 gb of ram and only 2 core of your quad core, hope i helped :D