Tweak Windows' Power Settings to Cut Your PC's Energy Use
If your system is using the default power settings in Windows, it may be adding unnecessarily to your electric bill. Find the right balance between cost and convenience when deciding how quickly your machine's components should enter their sleep mode. To access the Power Options in XP, click Start, Control Panel, Power Options (Start, Settings, Control Panel, Power Options if you use XP's Classic menu). In Vista, click the Start button, type power options, and press Enter.
Under XP's Power Schemes tab, click the drop-down menus to have your monitor and hard drive enter standby more quickly.
Restart XP faster via this option to put your PC to sleep rather than shutting it off when you press the power button.
Customize Vista's preset power options to reduce the amount of energy your PC consumes when it's not in use, without causing inconvenience.
Save time by setting Vista to sleep rather than to shut off entirely when you press the power button.