I've read that Windows 7 has some power saving features and have even heard claims of a 1 year Return on Investment in power savings.
However, all I found was reference to saving .5W by disabling the network adapter if it's disconnected, and reducing power to audio devices (if none are in use). I can't see this latter one having much effect since the bulk of my audio power is the external speakers and even if they are off, the transformer would be consuming power (I think) and certainly consuming power if on even at the lowest volume setting. (I.e., to save significant power on the audio you'd have to physically turn off the speakers and maybe unplug them.
Is it MicroHype? If not, how much power can Win 7 save on a desktop PC?