I just tried SLI hack with my HTPC but seems like there is something wrong in itīs bios or in the board itself.

Board is Asus P5E3 WS PRO with latest bios. If I add card in another slot my Vista X86 freezes in loading. Then I did take new HDD and installed Win 7 X64 to it but drivers did not install to that second GeForce 8800 GTS 512MB card, no matter what I did, with and without SLI bridge.
Driver version I tried was 190.89.