A correction was made to this story. Read below for details.
Microsoft announced Wednesday that people looking to save energy and reduce the environmental impact of their computer should turn off their screensavers. A Windows Vista PC running a screensaver consumes more energy than a PC in "Sleep" mode, according to a statement from Dean DeWhitt, the director of Microsoft's Windows Kernel team. In fact, the screensaver-running PC consumes the same amount of electricity as a 100-watt lightbulb left on around the clock for one year. That is about $80 in power that releases about 1,350 pounds of carbon dioxide emissions into the atmosphere, according to Microsoft.
Microsoft got the energy statistics on PCs from U.K.-based PC Pro Labs, which conducted an independent study on the energy consumption of Windows Vista vs. Windows XP computers in a work environment. Vista includes a "Sleep" mode, like on Apple computers, which pauses a PC for energy savings, but also allows users to "awake" the monitor and machine instantly to resume use. It is a modified combination of the "Standby" and "Hibernate" modes that were on previous versions of Windows platforms. Microsoft said the new mode could be useful to large organizations that require users to leave their PCs running, so that security patches and updates can be applied during non-business hours.
Correction: This story incorrectly described Microsoft's recommendation to turn off screensavers. It is Windows Vista specific. Vista's "Sleep" mode is a modified combination of the old "Standby" and "Hibernate" modes on previous Windows platforms.