The PC case. First, wipe out excessive dust or other obstructions from the opening for the power supply fan at the back of the case. Do the same for any ventilation openings. Clean the exterior of the case with a lint-free wipe lightly moistened with a very mild soap or ammonia solution. And remember the cardinal rule of cleaning a PC: always spray the cleaning liquid on the rag, not on the PC.

Motherboard, cards, and memory. Before opening your case, turn off the power. And if your system has any type of active soft-on or sleep mode (check your PC's manual), unplug the system from the electrical outlet; otherwise, you can leave it plugged in. Put on your grounding strap and clip it to the PC frame if your system can remain plugged into the wall power outlet. If it can't, you'll have to attach it to another suitable ground contact such as a plumbing fixture or other metal object.

Remove excessive dust with a brush and/or canned air. Remember, the object is to remove the dust, not just move it. So turn the case on its side first, or better yet, use a small vacuum cleaner to ensure dust doesn't just resettle.

Over time, expansion cards and memory chips can become partially unseated due to movement and even temperature fluctuations. Cleaning offers a good opportunity to reseat them. Use caution during removal and insertion. Wipe the contacts gently with a lint-free swab and, ideally, a lubricating solution. Cautiously do the same to the inside of each slot on the motherboard. And when you reinstall cards, don't overtighten the screw attaching the card to the case; doing this can partially unseat the card.

The keyboard. Turn the keyboard upside down and blow dust and dirt out from between the keys with canned air. Most keys can be gently pried off to expose the contacts below. Computer shops have special tools for this, but something soft like a pencil with the lead broken off will work nicely. Just be very gentle and apply an even pressure to opposing sides of the key as you lift. Take care not to lose any springs or grommets that may be on the underside of the key. The keys and exterior surfaces -- but not the contacts under the keys -- can be cleaned with a mild soap or ammonia solution on a lint-free wipe.

The monitor. Thanks to strong electrical fields, monitors are literally dust magnets. Wash your monitor's case with a mild soap solution and a lint-free cloth. Make sure all ventilation openings are dust-free and unobstructed. Monitors produce a lot of heat, so any blockage can cause high-temperature failure. Many monitor screens can be safely cleaned with ammonia-based window cleaners. Check your documentation or ask the manufacturer if your screen has any antiglare or other delicate coatings. If it does, you will have to follow special cleaning instructions.