You could use System Soap. This is a tool I use on my XP and it works well.http://download2.systemsoap.com/ssoap/indexpro.html
If you want to see these hidden files and folders, Open any folder, Click on Tools, select Folder Options, Select View and check in the small circle next to (Show Hidden Files and Folders) Now click on Apply to All Folders.
In My Documents select your own documents not All Users. You can view some of your recently used files and documents in the folder (My Recent Documents). You can if you like delete all these safely.
Now select the folder (Local settings). This folder looks faded compared to the rest, this is because it is one of the hidden folders. In this folder you will see a folder called Temporary Internet Files.
There are more of course, but it's much safer using a tool such as System Soap.
Another way is to go to System tools, select Disk Cleanup. This tool will remove most thing too. Hope this helps.