Clean Now Or Pay Later
Dust is your computers worst nightmare.
All PC's have internal fans to circulate air and vent hot air heated by your computers CPU and hardware.
Dust builds up inside your computer and acts as an insulating blanket that causes the computer to run hotter and can cause crashes to your system. By opening up the computers case and using an air duster that can be purchased at most office retail establishments you will add years of trouble free operation to your computer.

Air Needs To Circulate
Your computer needs space around it in order for air to circulate.
Putting the computer in a location where obstructions are directly next to or on top of the computer airflow will be restricted. This can cause the computer to operate at higher temperatures and could add to the causes of common PC crashes.