As much as we've all been tempted to just let loose with a fire hose on our dusty, dirty, smoke-grimed and grease-smudged PCs, you just can't do it. Here are some tips for cleaning dirty hardware as well as keeping the power clean and the engine purring.

Cleaning the monitor: Like any other CRT such as a television, the monitor attracts dust and dirt. Clean it with a lint-free cloth lightly sprayed with Windex or a mild ammonia solution -- don't let excess cleaning fluid run down into the monitor casing, and don't spray the stuff onto the PC, spray the rag. If your monitor glass has an antiglare or other special coating, make sure to follow the manufacturer's cleaning instructions.

Your mouse will pick up crud and start balking; the documentation provided with the mouse should tell you how to open it up and clean it.

Once a year (at least) you should open the computer's case and vacuum out the crud. (If this is worrisome, let a tech do it. Pay no mind if he sneers at you, it's better than having your fumble fingers destroy the computer's innards.) A lot of people like to use those little cans of compressed air to blow the dust out of there. These are fine, just make sure the dust blows out and not somewhere else inside the casing. Also, take the PC somewhere else to clean it; otherwise the dust you blow into the air will find its way right back to your PC. You can use a drinking straw and blow through it, directing the thrust to certain points inside the PC, but don't inhale unless you want to crack up your co-workers for the next month. Use an old (but soft) paint brush to loosen the accumulated dust from corners, fans, the mother board, etc. You'll probably do well to invest a few bucks in an antistatic wrist strap, to keep static electricity buildup from frying your PC's innards. And make sure the damned thing's turned off and unplugged before you crack the case! If you're really into it, you can (carefully) remove and replace the expansion cards and memory chips. Using lint-free wipes and isopropyl alcohol on the contacts and the insides of the slots should do the trick, but a lot of people prefer to use contact cleaner. When you reinsert the cards, make sure you don't over tighten the screws attaching the cards to the case, as this can partially unseat the cards.

Clean the keyboard by turning it upside down and blowing the dust out from between the keys with canned air. If you want, you can gently pry the keys off one by one and clean the key contacts, preferably with an ammonia solution on a lint-free wipe (not cotton Q-tips). Keys won't come off? Then they aren't made to come off, so quit yanking on 'em.

Power surges cause lots of trouble. Don't skimp on a surge protector; get a good one. (A good one will have the Underwriters Laboratory UL1447 rating. A better one will have this rating plus a response time of less than 1 nanosecond, indicator lights that warn you of failed components in the unit and of improper grounding in your building's wiring, ports for your external modem, and ports for any other line connected to the PC.) If it looks like an electrical storm brewing outside, shut the computer down and unplug both it and the surge protector. Even a good surge protector will melt if lightning or a heavy surge nails it, but hey, it's better to lose a $40 surge protector than a $1000+ computer. Also, keep the surge protector away from your feet, as it's easy to hit the off switch with a stray foot. A few more caveats: surge protectors age relatively quickly, especially in areas prone to power surges and spikes. Replace yours every 12-18 months. Modem phone lines need protection too. Most upscale surge protectors come with one or two RJ-11 telephone connectors; if yours has 'em, use 'em, or you can buy a modem protector separately. Ancient wiring, glitchy transformers, etc. can send nasty shocks through your system and cause problems, also, so be aware. Check out www.apc.com for info from a leading surge protector manufacturer.

Heat is a major villain in the PC world. The temperature inside your little box can easily reach over 100 degrees. Once the mercury starts spiking at around 110, you start frying components. What's a poor user to do? Well, there's a free utility out there called Motherboard Monitor, available for download at members.brabant.chello.nl/~a.vankaam/mbm, that monitors your motherboard's temperature and even e-mails you an alert when things get too hot for comfort. You can easily run a "fire drill" by installing this utility and then running two search sessions simultaneously through Start, Find. As the searches progress, temperatures inch up, and alarms go off. (Stop the searches to lower the temp.) And when you start adding peripheral devices, temps really climb. But what can you do to keep things cool, besides turn the beastie off? First, check the grate on your PC's power supply fan. If it's covered in cat fur, carpet lint, or general schmutz, get it off of there. One expert recommended covering your fan's intake grate with a piece of pantyhose to keep the gunk out. For good measure, disconnect everything, take the thing outside, and blast it with a can of compressed air. You can even crack the case and vacuum out the insides with one of those handheld jobbers, if you're carefu.. You'd be amazed how much crud comes out of there. If you really want to ensure that temps stay low, install either or both of these little goodies: the $29 Bus-Cool fan that goes onto a vacant slot on your motherboard, and its cousin, the $49 Bay-Cool, a device that blows cool air directly on your motherboard. Both are available at www.pcpowercooling.com.

Speaking of power supplies, you should be aware of several problems that can occur. Smoke is an obvious red flag; if you see it or smell it, turn the damned thing off right away and see if the smell or vapors subside. Then turn it back on (gingerly) and see if it starts up again. If it does, open up the PC's case and investigate. You probably have a problem that a tech needs to address, but it might just be burning cat fur caught in the grille. If you don't hear your fan going, it might be burned out. Shut your machine down and make arrangements to have your power supply replaced. If you're plagued with intermittent memory error messages, it may be that your RAM is becoming annoyed with power fluctuations. Make arrangements to have your power supply checked. A black screen with the PC going is often due to a monitor problem (or a monitor "asleep"), but it might be that the motherboard has detected a power anomaly and shut itself down to preserve itself. Lastly, if you have odd problems at start-up, such as memory errors or strange video displays, that don't manifest themselves when the machine is warmed up, your power supply may be heading for a breakdown. You have two choices of supply types, ATX and AT, depending on what flavor of motherboard you have, and of course, a few PC manufacturers use non-standard suply types. Check your documentation. If you're forced to replace your power supply, make sure your new supply module is compatible and strong enough -- at least 200 watts. If you've added new doodads to your PC since you purchased it, consider getting a stronger power supply than the original one. The new additions suck up power, too.

Never ever: unplug a peripheral (printer, monitor, whatever) while the computer is on; shut off your PC without exiting Windows; improve your computer (installing more RAM, upgrading your OS, whatever) without doing a full backup; open a file you've just downloaded unless your anti-virus program is running and in auto-scan mode; store floppies or backup tapes near a magnet, near a telephone, or even near your monitor; smoke near your computer (the smoke is highly corrosive to the electronic components).