QMy hard drive is getting crowded. Is there any software that can automatically clean up duplicate files?

ACertainly. Shareware authors have developed many inexpensive utilities for this task, such as Check Identical Files (Win 95 or newer, $15 at www.abc-view.com).

But you need to be careful when using these tools to free up space on your hard drive. They can flag items not worth the trouble to delete, such as the "readme.txt" files left by programs' installer routines. These documents are usually too small to bother worrying about.

Randomly removing other kinds of files can get you in trouble. Steer clear of the Windows and system directories. When in doubt, burn these duplicate files to a blank CD before deleting them, just in case you need to put them back where you found them.

But there's an easier solution to cramped hard drives. When readers complain about hard drives being full, most of the time the problem is one particular kind of file: multimedia. Go after the old picture, video and sound files littering your hard drive when you need to make room for new data or programs.

I heard about a group that launches cyberattacks against the regular customers of any company that hosts spammers. What do you think?

Vigilante justice makes for great box-office receipts; in the real world, however, taking matters into your own hands can yield unexpected, unwanted results. What if the wrong site is subjected to such a counterattack? What about the legitimate electronic traffic that gets stopped in the course of denying service to the right site?

The sad truth is that spam is profitable. It's irritating to most of us, but you wouldn't get the same junk e-mail over and over unless somebody, somewhere bought what the spammers advertised. Spam will end when people stop being suckers for the phony products it promotes.

-- John Gilroy

John Gilroy of Item Inc. is heard on WAMU's "The Computer Guys" at noon on the first Tuesday of the month. Send your questions to him in care of The Washington Post, 1150 15th St. NW, Washington, D.C. 20071 or via e-mail to jgilroy@iteminc.com.