Q When I buy a new PC, I donate my old one to a charitable organisation. Before I give it away, I'd like to remove certain files so that they cannot be recovered. What's the best way to do that?

A An entire cottage industry has sprung up around this particular problem, created by Microsoft's less-than-thorough Delete command, which dates back to the old days of DOS. A number of programs can overwrite a deleted file so that it can't be restored, including Norton Utilities, Nuts & Bolts, and PowerDesk.

Norton Utilities 3.0 for Windows 95. When you do a full defrag with Norton's Speed Disk, you also wipe clean everything on your drive that isn't currently assigned to a file. (Not all defraggers do this: Windows' Disk Defragmenter, for example, leaves some data where it can be found). For more information, see www.symantec.com.au.

Nuts & Bolts. Click the Secure Manage button and select Shredder. A wizard will walk you through your options, which range from wiping out one file to clearing all the unassigned space on your drive. (See www.nai.com.)

PowerDesk. This file manager won't help you wipe out all stray data, but it can clean a file off your disk safely. Simply select the file, and then select FileûDestroy. PowerDesk is available from www.mijenix.com.

If you don't have any of these programs, several shareware options are available. My favourite is Craig Christensen's US$20 Mutilate, available as a download from home.att.net/~craigchr/mutilate.html and on this month's cover CD.