What games is my computer capable of playing?

I've just put together this brand new custom made. I'm running a 600 gig hard drive, 4 gigs of DDR2 RAM, and NVidia GeForce 9800 GT, Sound Blaster Live 24-Bit, and I've got an AMD Athalon 64 X2 Dual Core Processor 4400+ 2.31 GHz. My Dad and I put this computer together and it runs beautifully, I play World Of Warcraft alot and my constant Framerate is 60+. I'm just wondering what its capable of playing, I don't want to buy a game, the computer not be able to play it and me not be able to get a refund. Also, if anyone could gauge how good this new computer is, like what its comparable to I'd appreciate that. My Vista Score is 4.9 with Aero Performance being the lowest and 5.9 being the highest with disk data transfer rate (Primary hard Disks) as a side note my second highest score with 5.3 is 3-D business and gaming graphics performance. thanks in advance for the advice/information.