Installing a water cooling system will dramatically cool down your computer making it run better and you will never have any more worries about your computer overheating, and also it makes your computer look very cool.

[edit] Steps

Buy a water cooling system from a computer store (online is usually the best) you can get the water cooling systems from website’s like NCIX.com, or tigerdirect.com.
Buy non-conductive water so if you spill it on your computer you wont wreck it (coloured ones look the coolest).
Get rid of the heat sink over top of your processor (if you don’t you wont be able to install the water cooling). This will have a fan and is in the center of the chip. Make sure not to rip the chip straight off the motherboard.
Clean the top of the exposed chip with an alcohol wipe and apply thermal paste (a conductive metal- or silicone-based grease that should come with the kit).
Install the water block. Install the water block using the provided mounting bracket. The mounting bracket will sandwich the mother board with a bracket on the bottom and the top connects with two screws. As always, and especially with electronics, don't over-tighten the screws.
Put your computer back together.
Know that once you have put your computer back together you can turn it on and check for any leaks.

[edit] Tips

If you’ re buying a water cooling system don’t buy the least expensive because it will always break on you.
Never use anything besides non-conductive water because you will always have problems
If you have a problem with following these steps there are several website’s you can goto like
http://www.popularmechanics.com/technology/how_to/4213273.html
http://www.smartcomputing.com/Editorial/article.asp?article=articles/2004/w1510/42w02/42w02.asp