If there are multiple administrators on same Windows XP machine then it becomes quite difficult to protect your privacy. Anyone can see any of your folder contents and private documents.
Free Hide Folder is a free utility to hide your private folders. No one else would know where are your personal files. You can also protect your folders by a password which you can change or remove anytime you want.
You just need to add a folder and then right click for options to hide. Free Hide folder is very light sized freeware (~750KB) and can run on Windows XP/20003, 2000/9x/Me/NT. You can download free copy from here.