Keeping older machines in service by simply extending the lifecycle or upgrading components can save five to 20 times more energy than by decommissioning and recycling old gear, the United Nations University study noted.

Another important component in an environmentally-sound desktop strategy is to turn the machines off when they aren't in use. This sounds like a gimme, but it isn't, says Matt Heinz, senior director of marketing with Verdiem, which sells PC power management software. "Eighty percent of users end up turning the default power management settings that ship with new PCs off within 60 days because it gets in their way," Heinz says.

Furthermore, IT departments often like to push automated upgrades and security patches out at night or during off-peak times. Many enterprises leave their systems on all the time to ensure these updates take place as planned, especially with older systems that lack robust built-in capabilities to reliably wake up the machines remotely, or in settings or when systems have to be accessed remotely outside a firewall.

Printing company Quad/Graphics, a Verdiem customer, runs 4,500 PCs in 12 printing locations and 14 sales offices nationwide. The company saved nearly $72,000 in power costs in 2007 by turning off PCs when they weren't in use, says Quad/Graphics spokeswoman Claire Ho. "We use 1.26 million fewer kilowatt hours from the electrical grid," adds Ho. That's the equivalent, according to the EPA's greenhouse gas equivalency calculator, of taking 179 cars off the road.

2. Buy Equipment with Energy Efficiency in Mind

According to a recent CIO survey, most IT shops recycle. Fifty-five percent of respondents say they use vendors' recycling or take-back programs, or otherwise dispose of equipment responsibly. But few organizations take energy efficiency or manufacturing processes into account when buying new gear — in fact, only 32 percent do so regularly. You can, without much effort, look for energy efficient equipment when it's time to buy.

According to a recent report issued by the Butler Group, an IT research firm, companies should ask vendors about the use of toxic materials in their products, and about the recyclability of the equipment. However, says Mark Blowers, who directs the company's enterprise architectures practice, it's more important to open communication with your vendors about the toxics in their products rather than to mandate a particular toxics profile. "You have to be realistic about what you specify, and balance your environmental goals against increased costs." Over time, as vendors realize that customers care about these issues, they'll adapt their product offerings.