In the modern OS systems, especially Windows Pro versions, you can assign user rights to certain folders. If you have administrator, and others are just users, then correct use of the user rights will prevent them either gaining total access to a folder, or just allowing them read only access.
Never tried it (I don't really need to spend time reloading my PC if it doesn't work
), but I would hope you need admin rights on the Win XP based systems to allow a format command to run. Of course if someone knows how to reboot and enter command mode, they will probably bypass that. All you are doing is stopping accidental erasure by prying fingers.