I got this from CNET.com:
Step 1: Keep your cool
Computer components--processors, graphics cards, and the like--get hot when they run. To mitigate this, laptop makers put in elaborate heat sinks that absorb the heat generated by the processor. In addition, all but the tiniest models have at least a single fan; some bigger systems have two or even three. When the temperature rises above a certain level, the fans automatically come on to keep the laptop out of the red zone. Unfortunately, like all fans, the ones in your laptop will eventually end up covered in dust and dirt, and that could spell trouble.
An occasional cleaning will keep your laptop fans spinning effectively for years. But before you can clean them, you'll have to find them. Fortunately, in most cases, they're near the vents that are located around the edges of your case; these slats let cool air in and hot air out. Don't worry if they're covered in dust and lint, we'll get to that. Now you'll need to open up the laptop case.
Look for a few sets of screws, underneath the laptop near the vents. Remove the panel and look for the fans--they're circular and plastic, usually about the size of a quarter, with a small propeller inside. Again, it may be covered with dust and lint.
Step 2: Dust bunny patrol
Now that you're inside the laptop, use a flashlight to look around for built-up dust and dirt. Using the eraser-end of a pencil or tweezers, pick off any nasty deposits you come across.
Start at the fan, then work your way to the ducts and vents. Look under the ribbon cables, around the hard drive, and near the tiny circuit boards. Grime can hide in the oddest places, like the processor's copper-colored heat sink, so make sure you explore all the laptop's nooks and crannies.
Step 3: Air it all out
You've done the detail work, and now it's time to go big. Put on a dust mask, if you have one. Grab the can of compressed air and spray down the inside of your laptop. Go nuts. Blow out all the dust you can find. It won't be pretty, and you might want to have a vacuum cleaner running nearby to grab all the junk it as it comes out. Don't be surprised if a lot comes out of that little laptop.
Step 4: Shake, rattle, and roll
Now that you've made your first pass at cleaning out the inside, give your laptop a little shake to dislodge any particularly resilient dust and grime. Keep cleaning and shaking until nothing more comes out.
Step 5: Key to the crumb highway
Now that the inside of your laptop is as clean as a whistle, it's time to tidy up that nasty keyboard. Don't be embarrassed by what you find: Most keyboards have enough crumbs to feed a flock of pigeons for weeks. Use the can of compressed air to blow it clean, but be careful not to break any keys off.
Step 6: Tighten up
While you've still got the laptop open, give each of the major components a quick look to see if any are loose. A loose motherboard or hard drive can cause damage in the long run, so make sure all of the screws are tight and all of the cables are well connected. When tightening the screws, be careful not to overdo it--gently tighten until you feel some resistance. When you're done, reconnect the access panels on the underside of your laptop.
Step 7: Clean your screen
All laptop screens are susceptible to nicks and scratches, and the latest glossy, high-contrast displays show off fingerprints that even Columbo couldn't miss. We like to give our screens a quick rubdown about once a week. You can use any brand of window cleaner so long as it doesn't contain ammonia or any harsh detergents. We're partial to Sprayway, because it gets all foamy and doesn't leave annoying streaks; unfortunately, Sprayway can be hard to find in some places, and you may have to make a special trip to a glass or mirror store to find it.
When wiping down the screen, stay away from tissue that leave lint behind or rough fabrics that may scratch the display. We recommend Kimwipes lint-free cleaning cloths, a soft cotton chamois or a microfiber cloth.
