Edison gives you detailed control over PC power savings

Computer power management: Good. Power management with a detailed description of how much energy, money, and CO2 you'll save based on each change: Even better.

Edison is a free tool from Verdiem, and it replaces the power management software built into Windows. Unlike the brutish Windows power manager, Edison lets you split the day into Work Time and Non-Work Time, with different power settings available for each portion. You may want your computer to never suspend while you're at your desk, but probably don't care if it snoozes the night away when you're asleep. You can also set the display-off and hard-drive spin-down time separately for each time period. As well, you can set what days and times comprise those periods, so if you regularly work late or on weekends you're aren't stuck with the default "Work Time" setting of 8 to 6, Monday to Friday.

The really cool feature, though, is being able to see how the changes you make impact the bottom line, financially and environmentally. The sliders let you run through a variety of scenarios: For example, turning the display and hard drive off after 5 minutes instead of 20 and suspending after 10 minutes instead of an hour during working hours will save about $2.50 a year (at an $0.089/kWh rate—you can customize that number as well) and eliminate almost 40 pounds of CO2 emissions.

Edison is free but requires registration in order to use. It's a nice upgrade over the built-in Windows power manager, and it's actually easier to use than Windows' version, so there's really no reason not to check it out.

Download the software here: Edison (for XP or Vista)