Edison, an easy-to-use energy-monitoring application, absolutely free.
Edison puts you in control of your PC energy usage by letting you:

Set Your Own Schedule
Tell Edison when you use your computer most

Save a little or a lot
Use the Edison efficiency slider to choose the level of energy savings you want to achieve.

See your savings
Edison will calculate your estimated savings based on the setting you choose.

Download Edison For Windows XP

Download Edison For Windows Vista

Labels: Energy, free download, freeware