7. Reduce the size of the Recycle Bin
The recycle bin, under Windows XP, reserves 10% of the space on your Hard Drive, which is a lot and this can’t be used for anything else.
How do we change this size'
Right click on the Recycle Bin and select Properties. Go to the ‘Global” tab and check the “use one setting for all drives” and change the slide to 3%.
Note: You can define whatever size you want and on each drive.

8. Reduce the space allocated to the system restore
The restore system creates a backup of your most important system files like the registry and user profiles etc and stores these files in a restore point. This is useful if you have a problem, but these files can quickly take up a lot of space in your hard drive.

How do we do this'
Go to the Control panel and double click on the system icon, then go to the “System Restore” tab and under “Drive Settings” click on “Settings”. Move the cursor to 5% (or 1GB) and click on OK to validate.
Defragment the Hard Drive
Windows XP is delivered with a disk defragmenter that is a light version of Diskeeper. The system performance is better once the files are backed up and put consecutively. This means that all the files in the folders are located consecutively on the hard drive.
The fragmentation of a drive is translated by two small parts of the total of the disk, which means that it needs to “work” to read and write to the disk. The Windows XP utility can not optimise the performance of your hard drive automatically; you need to run it manually.
While this process is running it is not possible to use your system, but there is no better defragmenter to be found for free. This is why it is preferable to purchase a licence for Diskeeper.
How does this work'
Double click on the “My Computer”, and right click on the partition that you want to defrag and select “defrag now” and “defragment”.
Or:
Go to the “Start’ menu and in the run field type “Dfrg.msc”. Next, select the partition to defragment and click on “defragment”.
For your information, the “DCOM Server Process Launcher” is required to launch the disk defragmenter; it is therefore preferable to leave this on automatic.
10. Diskeeper
Diskeeper is a more powerful tool then that offered under Windows XP. It includes functions to defrag faster and better, allowing you to defrag 300 to 500% faster.
The functions offered are the following: defragment in the background, the scheduling of the defragmentation, pause and resume the defragmentations. To see all the functions offered, take a look at the official site.
The hard drives are the slowest components of the PC, so you shouldn’t leave the fragmentation of partitions too long to recover the space as the execution time of programs and files will only increase.