The SLI fix has already been posted.

Quote Originally Posted by bingo13 View Post
5. If you are unable to enable SLI support with various versions of Nvidia drivers (especially 266 and up), please reinstall the OS with the latest BIOS installed. I know this is drastic, but the SLI key format has changed and the OS might not recognize the new key in the updated BIOS (especially if non released NV drivers were previously installed, drivercleaner will not clear this setting during an uninstall). This should not occur in future BIOS releases.