Ahh man. There's a hack for this to work, I forget what it is. Apple didn't follow the DVI standard properly so it doesn't work well with all video cards on PC, but I know it does work with some of the older NVidia GeForce cards. It SHOULD work with the new ones as well (with DVI of course) but there was SOMETHING that had to be done. I just can't remember what it is. I'd check out
www.hardocp.com, www.tomshardware.com and euhhh.. well, hardocp would be your best bet. It's for hardcore PC guys and moders.
I used to work as tech support for a video card manufacturer that made some NVidia based cards so I know it should work. I've had clients send me links to sites that explain how to do it. And I know Apple messed up cause they admitted it to us.