You can clean the outside of your computer case with almost any type of general household cleaner, but the process of cleaning the case's interior should be your primary objective. For one thing, the accumulation of dust will clog your computer case's air vents and diminish your fans' ability to cool your system. As your computer runs, two or more fans are constantly turning, circulating air through the case in an effort to keep its internal parts cool. Unfortunately, as those fans bring in air, they also invite dust into the case, and that dust settles on the components inside. If you ignore this buildup, the components will run at increasingly warmer temperatures, which may eventually result in permanent heat-related hardware failures.

Before you begin the cleanup process, make sure you shut down and power off your computer and then unplug all the cables. Next, set your computer case on a clean, lint-free surface (no, not on carpet). Some electronics retailers sell antistatic mats or antistatic grounding strips for this purpose. (Static discharge can ruin your computer's internal components.) Once you open the case, don't touch anything inside until you either place your hand on your computer case's metal frame or put on an antistatic wristband (sold by most electronics retailers) to discharge any static electricity you may be carrying.

You'll need to use a can of compressed gas to blow out the dust found inside the computer case, as well as eliminate the dust and pet hair often found on its front and/or rear air vents, at least twice a year (or more often if you live in a dusty environment or always leave your computer running) to improve air circulation and prevent overheating. Don't use anything wet, including soapy washcloths or alcohol-soaked cotton swabs, to clean the inside of your computer. Plus, before you begin blasting everything in sight with compressed air, take a moment and pick your targets. You need to remember to gently blow the compressed air onto the targets, using the wand that comes with the can to direct the airflow with precision.

While we're on the topic of compressed air, we should explain what it is in more detail. These so-called cans of "compressed air," such as Dust-Off from Falcon Safety Products (www.falconsafety.com), aren't really filled with air at all. Instead, they contain a variety of chemical formulations (depending on the desired pressure output) that are packaged in cans in the form of compressed gas. When exposed to air, the compressed gas changes form very quickly. For this reason, it's important to hold the can in an upright position before and during use to prevent a gas-liquid mixture from being expelled. This type of liquid can cause frostbite and burns if it touches your skin, and it can discolor plastics and other materials.

You'll also need to be extremely careful while handling the components inside the case, especially the power supply. Never open the power supply case, and don't insert anything into it; doing so can result in a severe injury or a fatal electric shock.

Holding the can of compressed gas as upright as possible (again, to avoid expelling moisture), spray it directly into the power supply vents on the inside of the case so that dust particles exit the back of the case. Then spray the other components within the case, paying close attention to all the fans. Be sure to spray through all of the ports and jacks on the back of the computer, too. However, don't blow compressed gas from the inside of your case through your floppy diskette, CD, DVD, or Zip drives because you might cause damage.

Be sure to blow dust out of the processor's heatsink and heatsink fan. Dust buildup here can reduce the unit's ability to wick heat away from your computer's hottest component. Many modern motherboards also include a chipset heatsink (and, in some cases, a chipset heatsink fan). Blow does from this area, as well.

It's also important to keep the inside of your computer case free of clutter. Even with clean, functional fans, components can overheat if too many cables are restricting airflow. Use plastic cable ties to carefully wrap cables together and tie them out of the way of fan paths.

Owners of laptop computers should never disassemble their laptops. Simply spraying compressed gas through any open vents or on fans is all that's required. Because laptops are so small, the accumulation of dust within them is rarely an issue.

If you use your computer in an unusual location such as a workshop, mechanic's garage, or any place where your computer may face a high risk of abuse, investigate whether a protective enclosure would be worth the cost. The price for these enclosures depends upon the size of your computer, but they do add valuable protection. Additional bracing can protect your computer from toppling over in a workplace. One reputable vendor for this sort of hardware is Black Box Network Services (www.blackbox.com).

In addition, keep in mind that even though your computer is fairly tolerant of high humidity, if it's continuously exposed to a humid environment, your components will begin to corrode. If you live in a coastal region, be aware that the high salt content in your breezes can speed up this corrosion process. A room dehumidifier may be a worthwhile investment if you face a situation such as this.