Make sure your computer is set to hibernate or power down after a period of inactivity. With Windows XP, you can adjust this in Power Options on the Control Panel and Vista has built-in energy saving features. Macintosh computers also have energy-saving settings found under System Preferences.

Most computer peripherals use power even when they're not on. Plug them into a power strip so that you can easily shut off the power to save energy.

When shopping for a new PC, look for one that meets the ENERGY STAR® requirements that went into effect July 20. The EPA estimates that the new requirements will save more than $1.8 billion in energy costs over the next five years.