I have installed Windows Vista on a nForce 4 based motherboard and have two "unknown devices" in Device Manager under other devices which have failed to install due to lack of drivers.
Under details it shows:
What are these devices?
Please check to see if your motherboard supports Game Port or Midi functions. Midi and Game Port functions which are not supported by Windows Vista. Please disable these functions in your motherboards System BIOS. Please refer to the motherboard user guide or documentation for more information on System BIOS settings.