Sleek and slim are the watchwords of the computer industry now as manufacturers seek to build ever more computing power into thinner packages in the affordable mini-computer category. With the much-anticipated Apple tablet due out soon, possibly in the first quarter of 2010, deciding whether to buy a new computer — as well as when to buy and what kind to choose — remains as vexing as ever. The greenest choice is to upgrade your existing machine. No matter how energy efficient a new machine is, 80 percent of its lifetime energy consumption occurs during production, before it even hits the shelves, says Barbara Kyle, national coordinator of the Electronics Takeback Coalition. However, if you have to buy new because your processor is too old to run current software, or because a job loss has deprived you of an office computer, here are some things to keep in mind.

Laptop vs. desktop
Think twice about choosing a laptop over a desktop. Laptop portability is great and can be a requirement for many professionals. But laptops are extremely limited in their upgrade options and are much more likely to be damaged in transport. If that tradeoff seems OK because the new small models are cheap enough to be considered disposable, remember that the biggest part of a computer's environmental footprint lies in its production. So whichever you choose, seek a model that will give you the longest life span, even if it means paying a bit more. A cheap machine that dies in six months (and takes all your work with it) is a computer you'll wish you never bought.

As for monitors, Kyle points out that LED-backlit LCD screens are mercury-free, a problem with standard LCDs, but warns that we don't yet know what environmental problems LEDs may pose.

Certifications and labels
Look for models selected by the Electronic Product Environmental Assessment Tool (EPEAT), created by the EPA and the nonprofit Greener Electronics Council. These bear an EPEAT Bronze or Silver rating based on 51 environmental criteria, 23 of which are required and 28 of which are optional. Largely using European Restriction of Hazardous Substances (RoHS) standards (including restrictions on cadmium, mercury, lead, hexavalent chromium and some brominated flame retardants), EPEAT requires incorporating a minimum of 65 percent reusable or recyclable components, a take-back service and the reduction or elimination of toxins in packaging. Silver and bronze models both meet all the required criteria; silver must also meet at least half of the optional ones.

For energy savings, seek out EnergyStar-rated machines. The EPA recently strengthened the EnergyStar requirements for computers, making them on average 30 percent more efficient than comparable machines. Also, the utility-funded 80 PLUS program is working to make computer power supplies 80 percent more efficient. When purchasing a desktop, look for the 80 PLUS label.

But what will you do with your old machine? Don't just throw it in the closet — if it still works, donate it promptly to a local organization before it's outmoded. Visit your local solid-waste department's Web site and look for connections to groups that reuse computers. If a local program doesn't exist, Goodwill locations will accept donated machines, as will the National Cristina Foundation, a technology-training group. Some manufacturers, including Dell and HP, will also take back products. If your computer no longer functions, look for a responsible recycler (who won't ship your computer to China or Africa to be dismantled in conditions that harm workers and poison local waterways) at the Electronics Takeback Coalition.

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