Defragging A Hard Drive Running Windows XP
There are two ways to begin:
Go to Start - Programs - Accessories - System Tools - Defrag
OR
Open My Computer Icon on Desktop

Right click on the (C:) drive - choose Properites

Click the Disk Cleanup button.

This might take a while depending on how large your harddrive is.

Make sure a check is in the box of the items you want deleted. Then click OK.

Click Yes. It will now clean up the disk. Again this could take a while.

When that is finished, click on the Tools tab.

Under Error-checking - click the Check Now ... box.

Put check marks in both boxes and click Start.

Click Yes. When you are finished defragging you will restart your comuter and this utility will run.

Now click the Defragment Now ... Button

Click the Defragmment button. 
It will begin analyzing your hard drive.
If there is a lot of red then you machine really needs to be defraggged!

Mine doesn't look so bad as I defrag at least once a month. 
This can take quite a long time, depending on how large your hard drive is and how fragmented it is.
So go have a cup of coffee, throw some clothes in the washing machine, take the dog for a walk.....
Remember - "A watched pot never boils."
I defrag weekly if I am doing a lot of multimedia projects.

My defragged hard drive now looks like this!
When it has finished defragging you will see this message.

Click the Close button

Now restart your computer so that disk check can run.
That's it!