Help File: Wiping your data from your computer

Q: How do I ensure my data's gone from my old computer before I dispose of it?

A: Dumping a file in the Recycle Bin or the Trash erases the computer's record of it, not the actual file. Scrubbing the file requires extra tools.

In Windows, the free, open-source Eraser (http://eraser.heidi.ie) can do the job, but first you need to expose normally hidden folders holding some critical data.

In Windows XP, choose "Folder Options" from the My Computer window's Tools menu (in Vista, pick "Folder and Search Options" from that window's Organize menu), click the Folder Options window's View tab and then the "Show hidden files and folders" button.

Then open the "Application Data" folder -- in Vista, "AppData" -- and right-click to erase it.

Eraser may balk at that, unfortunately; in that case, you'll have to drill down to individual folders and wipe them one by one. Start with any named after heavily used programs or their developers (for instance, "Mozilla" or "Microsoft," though the latter's Outlook Express stores data in a vaguely named "Identities" folder). Then you can wipe anything valuable in such standard, visible folders as My Documents.

On a Mac, things are simpler. In OS X 10.3 or newer, drag the contents of your home folder to the Trash, hit the Finder menu and select "Secure Empty Trash . . ."

In OS X 10.1 or 10.2, download the 2.1.2 or 2.3.5 releases of the free Permanent Eraser from the "Downloads" section of http://edenwaith.com.

If you'll sell or donate the machine, reload its original software and delete any leftover files and settings. On most PCs, you'd do that by starting the computer off its system-recovery partition, then choosing an option to erase the disk; check its manual for instructions. On a Mac, you'd boot from the system CD or DVD and select an "Erase and Install" option.

Next week, I'll explain a few options for donating or recycling old computers.

Rob Pegoraro attempts to untangle computing conundrums and errant electronics each week. Send questions to The Washington Post, 1150 15th St. NW, Washington, D.C. 20071 or robp@washpost.com. Visit http://voices.washingtonpost.com/fasterforward for his Faster Forward blog.