Jehan said..
Cleaning your computer can sometimes improve its performance in addition to making it look better. One example would be cleaning the dust that builds up around the fans designed to move hot air out of your computer's case. Cleaning up some of this dust can improve air circulation inside your computer and help cool components such as the processor and the hard drives. This can help prolong the life of these components, or at the very least prevent overheating related lockups and crashes.
To clean the dust that builds up on your case, you should use a can of compressed air, which can be purchased at any office supply store. Compressed air is also good for blowing out food and other buildup from the inside of your keyboard. Just turn it over and give it a few bursts of air.