My old computer finally bit the dust and I am in the market for a replacement. Are there any particularly "green" computers for sale these days?

-- Brian Smith, Nashua, N.H.

Thanks in part to pressure from nonprofits like Greenpeace International, which has published quarterly versions of its landmark "Guide to Greener Electronics" since 2006, computer makers now understand that consumers care about the environmental footprints of the products they use.

The latest version of Greenpeace's guide gives high marks to Toshiba, Lenovo, Sony and Dell for increasing the recyclability of their computers and reducing toxic components and so-called "e-waste" (refuse from discarded electronic devices and components). The group also credits Apple, HP and Fujitsu for making strides toward greener products and manufacturing processes, but emphasizes that even such top ranked companies have lots of room for improvement when it comes to the environment.

PC Magazine, the leading computer publication for consumer and business users, recently assessed dozens of personal computers according to environmental standards it developed in-house based on energy efficiency, recyclability and the toxicity of components. The publication also factored in various "green" certification schemes such as the U.S. Environmental Protection Agency's EnergyStar program, the European Union's Restriction of Hazardous Substances (RoHS) directive, Taiwan's Greenmark and the computer industry's own Electronic Products Environmental Assessment Tool (EPEAT).

The top choices for green desktop computers, according to PC, are Apple's Mac Mini, Zonbu's Desktop Mini, HP Compaq's 2710p and dc7800, Lenovo's ThinkCentre a61e, and Dell's OptiPlex 755. As for laptops, the greenest current models include Dell's Latitude D630, the Everex Zonbu, Fujitsu's LifeBook S6510, and Toshiba's Tecra A9-S9013.

Perhaps more important than the green-ness of your new computer is what you do with the old one. Stuffing it into the trash or setting it out for curbside pick-up may be the worst thing you can do with an outdated computer, as heavy metals and other toxins inevitably get free and get into surrounding soils and water. If the machine still works, donate it to a local school that can put it to use, or to Goodwill or the Salvation Army, either of which can re-sell it to help fund their programs. Another option is to donate it to the National Cristina Foundation, which places outdated technology with needy non-profits.

Once you've gotten rid of an old computer and outfitted yourself with a spiffy new green one, you might just want to score a few green accessories. Brooklyn, New York's Verdant Computing, which bills itself as a purveyor of "the greenest computer products on the web," sells remanufactured ink and toner cartridges, laptop cases made from recycled plastic, GreenDisk CDs packaged in recycled plastic jewel cases, solar-powered MP3 accessories, energy-saving printers and even a software program, GreenPrint, which modifies the print programs on your computer to economize on paper and ink/toner use. Verdant also has most products shipped to consumers directly from the manufacturers to save re-shipping.

CONTACTS: Greenpeace International, www.greenpeace.org; PC Magazine, www.pcmag.com; National Cristina Foundation, www.cristina.org; Verdant Computing, www.verdantcomputing.com.

Are there any efforts underway to green the air travel industry? It seems to me that it must be one dirty business from a pollution standpoint.