PC game programming is so sloppy. You can get a quad-core CPU, 4GB of RAM and 2x top-end GPUs with the latest drivers... and the game will still run like crap.
When you try the XBOX360/PS3 port of the same identical game, it runs... perfectly. Always. Hell, my 2GB of RAM and 2x GeForce 6800 Ultra on an AMD FX-57, CoD2 ran like poo, and the XBOX 360 port had better graphics and ran at 80+FPS. Go figure. I'm getting UT2k7 for the 360 and not the PC, possibly C&C3 as well.
That's one reason I've given up on PC gaming - no machine is EVER good enough. Not to mention consoles have taken over IMHO, just look at XBOX Live. No equally efficient and tight system exists for any other platform, and ROFL at Wii Online having to type in a billion-digit code like it's 1978.