http://www.techpowerup.com/downloads/724/RivaTuner_x64_signed_Drivers.html
Also found at http://download.guru3d.com/ among other sites.
Those using Vista 64bit can enjoy Rivatuner again.
Gentlemen!
Say really BIG thanks to our old good friends from www.techpowerup.com. They were extremely kind to sign RivaTuner drivers with their signature allowing RivaTuner to run under Vista x64 OS with no limitations.
Also found at http://download.guru3d.com/ among other sites.
Those using Vista 64bit can enjoy Rivatuner again.