You can do quite a bit to clean the average Windows XP system. Files proliferate, programs fall out of favor, viruses reproduce, e-mail clusters, and pop-ups populate. Throw in a little system neglect and before you know it, you have a messed-up system that badly needs cleaning.

Cleaning a Windows system is more about behavior than it is about one or two tasks. Granted, you need to do some remedial work to get your system back in peak condition, but once you do, keeping your system clean on an ongoing basis is much easier than doing the remedial work in the first place.

Essential tasks

In general, you should work on the most accessible parts of the system first and then move on to the rest. Following is a list of essential tasks to do even if you're really pressed for time.

* If you have only limited time available, get rid of unused and unneeded files. Archive your old-but-still-valuable files to get them off your system. When you have more time, you can go back and deal with your programs and your system as a whole. (Generally you should get your programs under control before worrying about your data, but the key here is time restriction. Working on programs simply takes longer than does taming your data.)

* If you have more time available, do a program inventory and remove the programs you no longer need. You'd be amazed at how much clutter this can remove from your system. Then go back and clean up your data and archive your older information.

* Get rid of spyware and spam and get your Internet environment under control. If you do this, you find that using the Internet can again become productive, rather than frustrating.

* Closely examine what your computer loads without your knowledge. This is one of the key places many people overlook (even when suggesting ways to clean your computer), but Windows encounters instructions to automatically load different programs from a myriad of places (most on the Web). These programs can hog resources and slow down your system's overall performance.

Of course, tracking down such unseen scoundrels can take a bit of time. When you have that time (and after you've done the other things in this list), jump in and try to figure out what's going on. Windows provides some utilities that can help, such as the System Configuration Utility (msconfig).

* If you really have some extra time, you can wade into the murky waters of the Windows Registry. The Registry is the centralized database that controls virtually everything that happens in the operating system. It is mind-numbingly complex and staggeringly obtuse for normal humans to deal with. However, you can do things in the Registry that you cannot do in any other way.

Working in the Registry is not for the faint of heart. Make sure you double-check every action before you take it. One wrong step and you can bring your system to its knees.

Precautions for safety's sake

Cleaning a Windows system necessarily involves moving things, adding things, deleting things, and sometimes renaming things. Any of these tasks, while necessary, can have unintended consequences. Heaven forbid you should delete a critical system file or wipe out the wrong data key in the Registry.

These precautions help you avoid the bad things:

* Don't delete files without knowing what you are deleting. If you're in doubt, simply move the file to a different directory or rename it. Then, if you restart your system (or the program) and find out you made a mistake, you can always move the file back or restore its original name.

* Make periodic backups of your system. If you're getting ready to do a huge cleaning session, you might want to make a backup right before you start. If you want to rely on an older backup, you might want to have it close by, in case you need it when you start your cleaning session.

* Be careful how you delete programs. In the wonderful days of DOS, in the misty past, programs usually consisted of a couple of files or all the files in a given directory. Not so in Windows. When you install a program, the installation program can move pieces and parts all over the place. When you run the program, it can move more of itself to still other places. Because of that, the best way to delete a program is to use either the uninstaller provided with the software or the Add/Remove Programs applet in the Control Panel. Don't just delete the main folder for the program — pieces and parts will remain scattered everywhere.)

* Know what you are doing with the Registry. The Registry is a largely incomprehensible place. Be careful when you are changing or deleting things in the Registry. In fact, you should create a backup of the Registry before you do any big changes, or simply export a data key when you are getting ready to make more minor changes. (A data key is geekspeak for a branch in the Registry.) Windows does not have a Recycle Bin for the Registry — if you delete something by mistake, you will be glad you made a copy ahead of time.

* If a new icon shows up on your desktop one day, don't double-click it. If you don't know why it's there, someone (or some program) has possibly deposited it there. If you don't know what it does, why double-click it and run it? A safer course of action is to right-click the icon, choose Properties, and then examine what programs the icon runs.

* Keep your original program discs accessible. If you change the a program's installation, you probably need the discs. If you delete a part of the program you shouldn't, you probably need the discs. If you want to reinstall the program, you probably need the discs. Just keep them close. And it wouldn't hurt to have any necessary software keys (those pesky ten-character — or longer — codes required to install or unlock your software) for the discs, either.

* Use only programs from reputable sources. There are lots of programs you can use to help with your system cleaning. You can download most of these programs from the Internet. However, some of the software you find on the Internet may not have been tested and can be reliable. If you download and run a program from a disreputable source, you could possibly infect your system with a virus or do some other system-crashing function.

The preceding precautions aren't in any particular order. They simply give you some guidance as you start on your cleaning quest. Rest assured, however, that you already possess the best safeguard you can have: common sense. Trust your common sense and it'll help you through a large number of the problems you may face.

As you're cleaning your system, keep a notepad and pen nearby. Jot down each cleaning step you take, along with any oddities you observe. This could be helpful if you later need to track down a problem that crops up.