Often programs make changes to your AUTOEXEC or CONFIG files, and save the older version under filenames such as AUTOEXEC.OLD or CONFIG.BAK. If you know you don't need these older files, consider deleting them. Don't delete AUTOEXEC.DOS or a CONFIG file ending in .DOS, .COM, or .EXE. If you have a plethora of AUTOEXEC and CONFIG files on your system, find out which one is the newest and move the others into a temporary folder you create just for this purpose. Leave them for a few weeks to see if your computer functions properly without them. If it does, delete 'em.

Other files ending in .BAK, .TMP, .~MP, .PRV, .---, .001, .002 (etc), .LOG, .OLD, .*$, .$$$, .??, .??~, .^*, .SYD, .MP, etc. are often unneeded duplicates of other files (be particularly careful with the .PRV, .BAK, and .OLD files). Verify that they are unneeded (if they're over a month old, you most likely don't need them) and delete them. Use the Find Files function to locate these files: enter something like *.BAK to search these files out. You can always delete files ending with .GID or .FTS as these files are created every time you use Help and the Help Search function (.GID files are always hidden; you'll need to activate the "Show all files" option in Explorer to find these babies). .CNT are related files that provide you with tables of contents for certain Help files. If you don't want them, get rid of the .CNT files on your machine. If you find the file WIN32S in \WINDOWS\SYSTEM, it's a leftover from when you upgraded from Win 3.x; you can safely delete it, just make sure you edit your SYSTEM.INI file to remove any references to it. Two other folders that can safely be deleted are MSCREATE.DIR and ~MSSETUP.T. If you back up the Registry a lot, you can safely lose the SYSTEM.1ST file. (When in doubt, leave the file alone.) And check to see if you have a folder in Program Files called Online Services. If you do, delete it. It's filled with old versions of AOL, CompuServe, and possibly Prodigy and MSN. Should you wish to sign up with any of these ISPs, contact them for current software, don't waste your time with what's in that folder. Check out your .TXT files; Windows tends to accumulate lots of garbage under that name, so if it isn't one of your documents, consider losing it. If you use MSWord, look for .WBK files; these are backups for Word documents that you may not need. Word also creates ~$*.DOC files when a document isn't saved properly; if all your documents are OK, lose these files. To be on the safe side with any deletion, create a special folder and move all potential deletees into that folder. Keep them there for a week or a month while you work with your PC. If you can start and restart your machine OK, and all your apps function properly, lose those files. Another kind of file that can usually be trashed are the .DIZ files, usually named FILE_ID.DIZ. This is a Description in Zip file, which just list the files in their particular ZIP archive. Once you unzip an archive, the accompanying DIZ files can be trashed. .GRP files are Program Manager Groups that, if no longer used, can be trashed. And don't keep unwatched .AVI or .WMV movie files around -- they suck up a tremendous amount of space.

What exactly are some of these files? .TMP and .~MP files are obviously temporary in nature, while .BAK files are backups for particular files (not entire disks). .GID files are Generated InDex files created by WinHelp, and .SYD files are backup files created by SYSEDIT.EXE (and can be safely deleted if you're sure you don't need them). Go to EXT Search at kresch.com/exts/ext.htm to find out what any file extension means (Win ME users, the System Editor, or SYSEDIT, has been replaced by the System Configuration Utility, launched with the MSCONFIG command).

Check out your C:\TEMP or C:\WINDOWS\TEMP directories periodically. Files in this folder can often -- but not always -- be deleted. Never delete files with a date later than the last time you shut the computer down -- a good rule of thumb is if the file is over a week old, and you've restarted your computer more recently than that, then delete em. Users who turn off their computers without going through the shutdown procedure accumulate gobs of temporary files. Lose 'em, after you shut down all your other programs. One way to frequently clean out your TEMP folder is to add the line DEL C:\WINDOWS\TEMP\*.TMP>NU1 to your AUTOEXEC.BAT file (open AUTOEXEC.BAT in Notepad and make the changes there). Or add a line to your Start Menu Programs listing by right-clicking the taskbar, selecting Properties, clicking the Start Menu Programs tab, and the Add button. In the Command line, enter DELTREE /Y C:\WINDOWS\TEMP\ and click OK. Accept the defaults for the rest of the process. Once you're out, select Start, Programs, StartUp, right-click "DELTREE," and select Properties. (Win 95 users, right-click Start, select Explore, navigate to the Programs/StartUp folder, right-click DELTREE, and select Properties.) Click the "Program" tab, click "Close on exit," and click OK. Note: This procedure works, but if run from AUTOEXEC, could delete the files before WININIT.EXE has run, doing damage to your machine. Better to run this from your Start Menu and avoid the potential for disaster. (Thanks to R.M. Duncan, a Microsoft MVP, for pointing this out to me.)

A glitch in Windows Millennium (and exacerbated by Norton System Doctor) can create thousands of zero-byte .INF and .CPY files, all of which take up valuable system real estate and cause trouble with installation of other programs. Many of them have file names similar to OEM#####.INF. Find them by hunting for OEM*.INF in your hard drive and delete all the zero-byte ones. A Knowledge Base article at support.microsoft.com/default.aspx?scid=KB;EN-US;q281967& gives you more info.

Clean out your Internet browser (or browsers) cache and history files frequently. The new versions of Windows have something called a Disk Cleanup Wizard that claims to handle this task for you, but it doesn't do much of a job. Handle it yourself. Need pointers? A later page of my site has instructions on cleaning browser caches.

Although the Disk Cleanup Wizard doesn't handle browser caches particularly well, it does a better job with cleaning up other temporary files. Use it as a part of your regular maintenance routine, just don't think that it does the job on its own. You still have to scrub the virtual baseboards yourself. Its basic categories of Temporary Internet Files, Downloaded Program Files, Temporary Files, and Recycle Bin, are relatively self-explanatory and can usually be emptied with little forethought (except for the Recycle Bin, if you want to be doubly careful). The More Options tab uses the Add/Remove applet under Control Panel to hunt for other files that may not be of use.

Go through your computer and hunt out programs that you haven't used lately. Decide whether or not you need those programs to stay on your hard drive. Win 98/ME users, be aware that you have two large and possibly worthless files -- 30MB of Desktop Themes and 31MB of WebTV for Windows. These can easily be deleted to save space.

Millennium users, you have a glitch that works hand-in-hand with Norton System Doctor to strew useless, zero-byte .INF and .CPY files throughout your hard drive. Both Microsoft and Symantec recommend hunting these files down and exterminating them. Find out more from Microsoft's Knowledge Base article at support.microsoft.com/default.aspx?scid=kb;EN-US;q281967.

MS Office users tend to accumulate lots of unnecessary files beginning in _OFIDX or FFASTUN. These are indexes from Office's FastFind feature (from Office 7.0 and Office 97, respectively). You can delete them, but Office will just recreate them. To stop Office from creating them, remove FastFind from the Windows\Start Menu\Programs\Startup folder; you will, however, find that text searches are slower.

Fred Langa of www.langa.com/ gives us an excellent little cleanup batch file, appropriately titled CLEANUP.BAT. You can find download and use info at www.langa.com/cleanup_bat.htm. Actually, Langa has given us four versions: one for novices that cleans slightly less efficiently, but can be trusted not to wipe out needed files, another that is designed for the more knowledgeable user, and two that should be used only with gloves and a mask. Want more info? Check out Langa's column at content.techweb.com/winmag/columns/explorer/2000/18.htm and the followup at content.techweb.com/winmag/columns/explorer/2000/19.htm.

Some of us end up with half a hundred unused screen savers clogging up our machines. That dancing baby was cute five years ago, but who wants to see him now? Sometimes screen savers can be deleted by going through the Add/Remove applet in Control Panel, but most don't give that option. To hunt down unwanted screen savers, open the Windows/System folder and look for the corresponding *.scr file. (Switch to Details mode and click the Type column heading, so that all *.scr files appear together.) Ditch that file and the screen saver is gone for good.

Windows XP includes an uninstall utility that makes it simple to remove unneeded or obsolete versions of a program. To uninstall a program installed with Windows XP, follow these steps. First, click the Start button and then click Control Panel to open the Control Panel window. In the Category view where you see a list of Control panel categories, click the Add or Remove Programs hyperlink to open the Add or Remove Programs dialog box. In the Classic view where you see individual Control panel icons, double-click the Add or Remove Programs icon. Click the Change or Remove Programs button on the left side of the Add or Remove dialog box to display the Currently Installed Programs list box. Click the program you want to remove in the Currently Installed Programs list box (when you click a program name, the description expands to include a Change/Remove button or separate Change and Remove buttons). Click the Change/Remove button or the Remove button if Change and Remove are separate. Click the OK button in the alert dialog box that appears to confirm your removal of the program. When the Uninstaller finishes removing the program, click the Close button to close the Add or Remove Programs dialog box and to return to the Control Panel window. Use the Windows XP uninstaller to get rid of any unwanted program that you've installed with the Add or Remove Programs Control Panel. Using this utility to remove a program (rather than just deleting the program folder) ensures that all vestiges of the program are removed from the system and that you get back every byte of storage space to which you're entitled.

Okay, you've deleted a file, or a bunch of files, and you want them back. Windows won't give you much recourse in the programs bundled with the system, but in many cases, you can get those deleted files back. Files that you delete aren't really deleted until the system overwrites the physical data on the hard drive; depending on what you do with your computer, these files may be available for hours, days, or even weeks and months later. When you first delete a file, Windows simply removes your access to the file. The first thing to do once you realize you've deleted a file that you want back is to stop using your computer. Don't save anything, don't turn it off, and don't even install a recovery program (yet) because you don't want the file to be overwritten. If you're going to use a recovery program, run it from a disk. If you delete a file to the Recycle Bin, the first thing to do is to go into the Bin and see if the file is still there. If it is, just right-click and restore it. That's not always going to be an option, but don't give up yet. You'll probably want to use a recovery program. Several are available, none for free, but if you want the data, you'll want to spend the bucks. Start with the $29 Briggs Softworks Directory Snoop at www.briggsoft.com/dsnoop.htm, and cross your fingers.