Power on your PC when you begin computing on any given day and don't power it off until you finish for the day, unless you need to keep your PC on all the time.
Some people turn their PC on and off throughout the day. Big mistake. Doing this causes a computer's innards to frequently expand and contract from warming up and cooling down, creating stress that can lead to premature component failure.
Defragment your hard disk periodically. The operating systems of typical PCs and Macs scatter file fragments over the hard disk. Programs such as Norton Utilities combine these fragments, which reduces hard drive wear and tear and increases system performance.
Some programs signal you to defrag when your hard disk reaches a specified level of fragmentation, such as 90 percent. Alternately, you can defrag weekly, monthly or semiannually depending on how often you use your PC. Don't use a program that defrags your hard disk continually -- it will create more wear and tear than it prevents.
Periodically scan your hard disk for file system errors and fading magnetism with a program such as Nuts & Bolts. Do this once a week if it's critical that your hard disk be reliable, or once every month or two otherwise. Check for computer viruses. You'll probably never experience one, but why take chances? With a program such as McAfee's VirusScan, scan all programs you download from Internet file libraries and any floppy disks you borrow from friends or co-workers.
You can't catch a virus from reading e-mail, but be careful about e-mail attachments. Many people delete an attachment if it comes from someone they don't know.
Unplug your PC and any telephone lines leading to it during a thunderstorm, unless you need to keep your PC on for work purposes. A nearby lightning strike will blow right past a typical surge protector and can fry a PC. But be sure to use a surge protector to guard against smaller surges. Regularly back up any crucial data on your hard disk to a tape, removable hard disk or floppy disks. Back up daily or weekly, depending on how much new data you create. Consider storing your backups off site in case of a fire or flood.
Use a floppy drive cleaning kit when you experience problems with your floppy drive or, at most, once a year as preventive maintenance. Don't use one of these kits every week as some kit manufacturers suggest -- this just overstresses your floppy drive's read/write head.
Keep CD-ROM discs inside a caddy or jewel case when not in use to avoid scratches. If dirt or fingerprints sully a disc, gently wipe it with a soft lint-free cloth, or use an audio CD cleaning kit. Use a screensaver if you enjoy its entertainment value or modest security features, but don't expect it to prolong your monitor's life. Screensavers used to do this, but newer monitors prevent a stationary image from burning permanently onto your screen.
On the other hand, take advantage of the energy-saving features of newer monitors. By directing your monitor to automatically power down after a specified period of inactivity, you'll increase its life span.
Clean your monitor if it becomes smudged. But stay away from glass cleaners -- they can remove a monitor's anti-glare finish. Use isopropyl alcohol or distilled water along with a lint-free cloth. Wet the cloth first, then wipe the monitor. Periodically open your computer's case to clean out dust -- every year or two or more frequently if your PC is in a dusty area. This will help prevent heat build-up, which can shorten the life of system components.
Use either a portable vacuum cleaner or compressed-gas duster. To minimize static discharge, avoid older vacuum cleaners and brush attachments and prevent the metal of any vacuum cleaner from touching your PC.
After vacuuming the inside of your PC, vacuum the grille in front and your keyboard.
Before working inside a PC, ground yourself -- turn off your computer, leave it plugged in and touch an unpainted metal surface inside the PC. Your PC should be plugged into a three-pronged grounded outlet, preferably on a dedicated circuit. Don't move a PC or connect or disconnect its cables while it's on. If your mouse starts misbehaving, take it apart and clean it. Shake out dust, or use a cleaning swab or compressed gas. Don't smoke around your PC. The same tar that gunks up your lungs also will coat the innards of your PC.
Reid Goldsborough is author of "Straight Talk About the Information Superhighway." He can be reached at firstname.lastname@example.org or members.home.net/reidgold.