the only available driver for downloading is this one. Directing Windows to upgrade from the downloaded C-MediaCM6501_Audio_V60070207_vista.zip gives the same "native" Windows driver.
Well, when carefully looking into "C-Media CM6501 Lik Sound Device" setting ... isn't it...
I have Windows 7 (64bit) on Asus M2N-SLI motherboard. It happens that sound device is properly identified (C-Media CM6501) and corresponding driver is added by Windows 7.
However, there is no sound coming to headphones, although sound icon shows moving. The microphone works.