Overheating Computer is BAD!
The one thing computers hate more than anything is heat. The more heat there is the slower a computer will perform, and that is not the worst of it.
If a computer gets hot enough it can fry your computers hardware and now you are looking for a new computer or at least an expensive repair.
Some tips for preventing this from happening; First, make sure you have good ventilation for your computer. A computer has lots of fans to move air through the case and keep the parts cool, If you keep it in a cabinet or a tight spot the fans may not able to do their job well. Second, DUST. A computer just like you likes to be clean, Dust build up can prevent fans from doing their job at all.
The above picture is what happens when you do not dust your computer regularly and can lead to irreversible damage to your computer, and the summer months can make your dust problem even worse!