This item is from the PC Hardware FAQ, by Willie Lim and Ralph Valentino with numerous contributions by others. (v1.25).
Clean the outside with a damp (not wet) cloth with a mild dish washing detergent after unplugging the system. Let it dry completely before plugging your system in. Do not clean the inside - computer components are not susceptible to common house hold dust. Unless you have special equipment, you will more likely cause more harm than help to your computer if you try.
 
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