HelpFile: Scrub your old computer clean
Q. I just got a new computer, and now I need to dispose of the old one. What do I do?
A. Whether you donate or dispose of the machine, you first have to scrub it of your data, then restore its software to factory condition.
Because dragging files to the trash leaves traces behind, you need to use extra software to make them vanish. In Windows, use the free Eraser (heidi.ie/eraser) to cleanse the C: drive's "Documents and Settings" folder. Don't worry if it can't zap a few system files there; your data will be gone.
On a Mac running recent releases of OS X, drag the contents of your home folder to the Trash, then go to the Finder menu and select "Secure Empty Trash." With older software, you'll have to erase the whole hard drive; visit support.apple.com and search for "107437" in the "Ask a Question" field to see how to "zero all data" on a disk.
Then you can reload the computer's original software. On a PC, check the manual for how to perform a system recovery, usually done by starting the computer off a special part of the hard drive. On a Mac, boot from the system CD and follow the installer's prompts.
If you can't sell the computer, donate it. Local groups such as the Capital PC User Group (cpcug.org/reboot) and Washington Apple Pi (wap.org/about/donations.html) will refurbish old PCs and place them with needy recipients. Readers have also suggested the National Cristina Foundation (cristina.org).
Machines unfit for further use should not be dumped in the trash, because of the toxic metals they contain. But computer vendors such as Dell (dell.com/recycle), Hewlett-Packard (hp.com/recycle) and Apple (apple.com/environment) can take back old hardware for safe disposal. You can also drop it off at a local hazardous-waste facility (see eiae.org for a directory), but you may have to pay a small processing fee.