One of the most common gripes we've seen in message boards all around the Internet involve users not being able to install AMD's Cool & Quiet drivers on Windows Vista, and therefore not getting the power saving effect. AMD's driver Web pages only contain C&Q drivers for Windows XP.
C&Q has been around for a few generations of AMD processors and, provided the chip is installed on a compatible motherboard, it regulates the CPU's multiplier and voltage to go into low power states when the full processor power isn't needed. Since most motherboards contain intelligent circuitry for their CPU fans, the fan will usually slow down when the CPU isn't running hot enough to require full cooling force.
Microsoft, Windows Vista