When you purchase a hard drive for a computer, one of the choices you may need to make is if the hard drive will be a 7200rpm hard drive or a 5400rpm hard drive. As you may have already guessed, the rpm of a hard drive is one of the factors that is considered in assessing a hard drive’s speed, and a 7200rpm hard drive spins faster than a 5400rpm hard drive and therefore can access data faster.
One of the problems with 7200rpm and faster hard drives is heat. When it comes to computers and their components, heat is a killer. A 7200rpm hard drive (and even a machine with two 7200rpm hard drives) should do quite well in terms of heat. Once you start moving to hard drive that run at 10,000rpm or more, however (e.g. Seagate Cheetah drives), then you need to consider special cooling for the drives to keep the temperature of the computer down to a safe level.
So for desktop machines, I recommend 7200rpm hard drives. You may pay a little extra but the performance increase you will see is well worth the few extra bucks. Laptop hard drives are a different story — you can read my post on that specific topic to see what kind of drive to put in your laptop computer.