it depends on how familiar you are with using ntfs security permissions in windows xp/7.in ntfs formatted drives you can set security permission on the root of a drive & then by inheritance rule can transfer permissions to all child objects inside that drive.by default group "everyone" has access.you can remove it & specifically set "guest" user group to deny even "read" permission so when someone logged in using a guest account try to double-click on drive icon in my computer an error message saying "you do not have sufficient privileges to access" will appear.