Windows XP File & Folder Special Permissions

Special permissions are customizable sets of permissions that you can apply to files and folders stored on an NTFS-formatted partition. If your computer doesn't belong to a domain, you'll need to disable simple file sharing in order to set these permissions. KB article 308419 explains what all the available special permissions are and how to view, set and remove them:
http://support.microsoft.com/kb/308419/en-us