Vista 64 bit won't accept second vid card

Need help.

I got my new box together, GA-EX38 DS4, Q9300 CPU, 8800GT card, and 8gigs Ram. After flashing the bios everything went together well until I installed a GeForce7600GT in the 2nd PCIe slot (for four monitor setup).

That's when I had to pull the 7600 out and use a restore point because of the BSOD.

I reinstalled the 7600 and tried again after the system got back, and then more trouble; the machine wouldn't start. It tried and then died over and over like that until I pulled the power plug and yanked the 7600 card out and restored again.

What can be causing this? I know this is a big question to ask, but as I said; everything else about the new build works fine. Am I forced into using one card?

Oh, I also tried installing the drivers for a FX500PCI card, but the forceware nVidia had isn't compatible with this machine, or so it said.

I really need to have the four monitors working.