Just 3 weeks ago, I got myself a new desktop rig.

These are the specs:

Intel Core 2 Duo E6750, BOX, LGA775
Asus P5N32-E/SLI, Nforce 680I SLI, Socke
Corsair TWIN2X2048-6400C4, 2x1024MB
Corsair CMPSU-520HXEU, 520Watt 1
Seagate 7200.10 160GB, 8MB, SATAII
XFX GeForce 8800GTS, 500M, PCI-E

So anyway, after about 2 weeks, it's been running fine, but then I inserted my previous 120GB IDE/ATA harddisk, for some old files and more space. When I turned on my computer again, a high-pitched sound started. At first I guessed it was the harddisk, so I turned it off, but the sound was still there.
I've traced the problem to the GFX card.
Now, at first, I thought it didn't really matter, seeing as I've experienced similar stuff, so I turned on my computer, and started a game of Bioshock. Within 20 seconds of gaming, the game locked up. The sound keept running in the same track, and changed every 4th second like "Bo-bo-bo-bo-bo-bo-bo-om-om-om-om-om-om".
So, I've tried reinstalling my GeForce driver, didn't change anything. I've tried older drivers, didn't help either.

What do you people suggest, and is this a typical problem? If it's a card problem, there is a warranty, and I can probably just go and return the card, though I don't want to be without my desktop for that long.

I really need some help here, I'm completely blank myself

Thanks in advance!