Uh.
Backup your files, take it to a tech shop, get them to reinstall Windowz, reinstall your programs and move your files back.
Also, while you are there, get them to add more RAM. Will help things a lot.
Problem solved.
If you think it's just your computer being old, this desktop is over 8 years old running Ubuntu Linux, which is a pretty hefty Linux distribution, and it's still fast as lightning. It was fast as lightning when it was running Windows XP, too.
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