How quickly computers age. You just bought a new PC with basic software and some version of Windows installed, and you want it to stay young and beautiful. What should you do? Here are some handy hints.

Be stingy with software. The foolproof way to keep a computer healthy is simple: never add new hardware or software. But in the real world, change is inevitable, and the computer industry has proved adept at exploiting customers' fascination with upgrades. Here, then, are my golden rules on software upgrades:

1. If it ain't broke, don't fix it. Although Quicken 6 is now in the stores, I'm still using Quicken 2 and loving it. Why change?

2. Don't buy software ending in ".0," which often signals new features that may be inadequately tested or frustratingly buggy.

3. If you do need new software, go for the older version. For example, if 3.0 is the latest thing, see if 2.0c or 2.1 has what you need. These earlier versions are likely to have fewer bugs, and because they were designed for older machines, they typically run much faster.

Watch what you're doing. Before installing new software, take a snapshot of your existing system so you can learn how the installer changed it. Some uninstall programs, like Quarterdeck's Remove-It (www.qdeck.com), include logging utilities for this purpose. Or you can create batch files that track changes for Windows 3.x. Users of Windows 95 and 98 should also back up the Registry.

Back up to basics. Do a complete system backup before making any major change. If you're just installing some small shareware or freeware items, you must first make backups of the most important system files: autoexec.bat, config.sys, win.ini, system.ini, user.dat, user.da0, system.dat, and system.da0.

Take your time. Never install multiple programs or drivers within a short time span. Wait several days between installations to make sure the latest addition works and hasn't messed up anything else. If you install five programs in one day, you'll have trouble determining which one made something go wrong. Before deleting any programs or files in your Windows folders, back them up on floppy disks or in a temporary directory, and keep them for several days or weeks before you delete them.

Get a good driver. Many seemingly unrelated system problems arise from buggy drivers for video, audio, and other hardware. Make sure that you have download access to the latest drivers for your hardware. Don't install new drivers willy-nilly, but do try to obtain the latest drivers if your system acts quirky. As always, keep the old drivers on hand in case you want to revert. The instructions accompanying the new drivers should specify which files are being upgraded.

Be a pest. If you experience problems ù from documentation to crashes ù let the responsible manufacturer know what needs improving. And thank developers when they do things right.

Bash bloat. I admit it: I run half a dozen doodads invisibly on my system. But the more accessories you have in a StartUp group (Windows 3.x) or folder (Windows 95, 98, or NT 4.0), the longer Windows will take to load and the more crotchety your system will be. Likewise, avoid installing billions of unnecessary fonts.

Keep it clean. Keep your hard disk lean and mean by limiting the amount of junk it accumulates. Here are three key rules:

1. Select the Custom option in program installers so you can decide what parts of a program to install.

2. Limit the amount of disk space your Web browser uses to cache files.

3. Open the Temp folder in your Windows folder occasionally and delete all files with dates older than the current date. Windows or applications may still be using files with the current date, so leave those files alone.

Caption: Unclog your hard disk by periodically deleting older files from your Temp folder