Defragment-XP
Many say that the Defragment-XP program that comes with Windows is not the best, but I find it to be adequate.What I mean, is that you will probably get satisfactory performance from a home computer.
If you have a heavily loaded computer that you use for business, then you probably need something better.
I’ve found that Diskeeper is much better. If you want this, plan to pay a few bucks,but for best performance, try it!
These instructions apply to the standard Windows Defrag tool.
Let’s get started.
Click on Start (lower left hand corner of your Windows XP screen)

Click on All Programs
Move cursor to Accessories
Move Cursor to System Tools
Move cursor to Disk Defragmenter

Your screen should look like this.
Then, click on Disk Defragmenter
You should get this:

n this picture, there is only one drive (C:) C: is the main hard drive for most systems, and this is the primary one to defrag. In this drive you see it has 112GB, and has 84% free. This is very good.
Note:
On some older systems, you might see 20GB drive, and less than 20% free. If you have less than 25%, you can expect severe performance problems.
If you have less than 80GB hard drive, and less than 40% free, should seriously consider upgrading to a new hard drive. You could add a drive, or have all of your information moved from your old hard drive to a new drive. Seek professional advice, before you decide.
Click on Defragment

Notice that the red files are gone, and the blue is mostly to the left. This is a typical picture of a properly defragged drive.