There seems to be too much saved in the windows folder.
The above is a bit of an "under-statement".
Hard Drives, particularly the hard drive that contains the Operating System, (Windows XP) need between 25%-50% to function adequately. Once the Free Space drops below 11% Windows will even be unable to Defrag and perform other disk maintenance functions.
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You will need a CD/DVD Burner or External Hard Drive, or a second machine into which you can Slave that Hard Drive, in order to SAVE various Media and Documents that presently reside on the Hard Drive.
Initially set your Goal at 25% Free Space and then we can have another look at the machine's performance.
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The machine does have a couple of application programs that are not strictly "necessary" and can be uninstalled or swapped for other applications that are not as demanding, while still providing the same function.
But those few application programs do not account for the overwhelmingly used up Hard Drive space.
What you will need to do is SAVE to external location like; (External Hard Drive, second hard drive, CD/DVD or Online Data storage) any important files, data, documents and media that the owner wishes to preserve.
Since the machine appears to have only CD-ROM, you will need to obtain an external CD/DVD writer or obtain and install an internal CD/DVD burning unit. Or obtain an external USB connected Hard Drive, or remove the Hard Drive and Slave it in another machine that has extra Free Space or has CD/DVD burning capability.
Keep us posted with your progress.
Once you get a large portion of the saved data, documents, and media saved to external location, and have deleted those related files, we'll need a fresh PCPitstop Full Test TechExpress so we can proceed to work on the other important maintenance that needs to be performed on this machine.
Best Regards