With Earth Day approaching, you're probably thinking about the different ways you can do your bit for the environment. Well, if you're reading this, it's a pretty safe bet you're using a computer, and computers generate waste in all kinds of ways. But by changing just a few habits, you can keep more stuff out of landfills, save energy, and even tuck a few extra dollars in your wallet. Here are five ideas to get you started.

1. Save paper and ink

I receive a lot of press releases and other printed documents that I never read more than once (if ever), so when I can get away with it I print on the reverse side of these pieces, reserving my pristine sheets for letters and other important documents. The savings are tangible: I've bought exactly one 500-sheet pack of paper in the last two years.

You can save more paper by shrinking your text and printing two pages side by side on one sheet of paper, if your printer driver allows it. (You'd better have good eyesight, though.) In Windows XP, choose Print, and then select Preferences or Print Setup. Look for an option called 'Pages per Sheet', and set it to 2.

If you print a lot from the Web, you should absolutely download a copy of the ad-supported GreenPrint World so that you can trim the stuff you don't need printed, which saves both paper and ink (or toner).

You can also save ink--easily the most expensive part of any inkjet printer--by printing in draft mode whenever possible. Look for more tips in "The Cheapskate's Guide to Printing."

2. Stop wasting CDs and DVDs

I can't count the number of times someone has burned a disc just to give me, say, 100MB of data, leaving the remaining 600MB (or, worse, 4GB or more) unused. Rewritable discs cost more and take a little longer to burn, but they're perfect for passing data back and forth without throwing out all that metal and plastic.

When you're done with your discs, you can recycle them by sending them to GreenDisk for responsible destruction and reuse. You must pay a small fee--$6.95 for boxes 20 pounds or lighter--but you can also cram in any other electronic waste you have lying around. Though GreenDisk guarantees that the material on your discs won't fall into the wrong hands, the extracautious can protect their data beforehand using Aleratec's CD/DVD Shredder. Despite its name, the CD/DVD Shredder actually pounds thousands of tiny pits into the surface of a disc, rendering it unreadable. Aleratec doesn't sell it anymore, but it does turn up on Amazon and eBay.

3. Tweak your power wettings

If you're like me, your computer is on all day, but you don't work on it continuously. Turning it on and off isn't an option, but a quick trip to the Windows Power Options control panel can shave your usage down a bit. There, you can set your monitor and hard drives to power down when you haven't been using the PC for a while. It takes only a second for them to power up again, so you can use that time to get comfortable in your chair.

Most important, you can set the computer itself to go to sleep or to hibernate after a certain period of inactivity. Sleep mode is a low-power mode, and as with the hard disks and monitor, it has everything up and running in just a few moments when you want to start working again. Hibernation, in contrast, switches the computer off but saves your current work environment first. As you'd expect, waking the computer up from hibernation takes a bit longer.

Tip: Windows XP SP2 sometimes has a problem making hibernation work when your PC has more than 1GB of RAM--oddly, it generates an error message saying that you don't have enough resources. A quick visit