Using the Disk Cleanup utility in Windows XP is a great way to clean up files and get more hard drive space. One of the options is to “Compress Old Files”, but the default setting is files older than 50 days. This setting can be modified if you only want to compress really old files.
To get to the Disk Cleanup utility, right click on one of your hard drives in My Computer, and choose Properties.
Click on the Disk Cleanup button.
The Disk Cleanup utility will scan your hard drive to determine the amount of space to be saved. Click on “Compress old files” in the list, and you will notice the View Files button change to Options. Click that.
In this resulting window you can change the amount of days to wait for unaccessed files to be compressed. Click OK and you are done.