Defragment: Optimize Your Hard Drive Fragments of data (like building blocks) get scattered across a hard drive over time.  Windows will begin to act sluggish if these blocks of information are not put back in their proper place. It is kind of like kid's not cleaning up their room. This leads to a dangerous mess of data on a hard drive. Defragging the drive is one of the best and effective things to do first if when a computer is acting slow. This will not change the speed of a system, just the time it takes to find the data on the hard drive. Defragmenter can be found under your start menu, program files, accessories, then system tools folder. (Assuming you are using Microsoft Windows XP Home or Pro.) Keep in mind that cleaning up temporary files, programs not longer used, start-up files, and running scandisk are also important in this process.