dont forget 1 biggy!
I got court by the misses on this one...
once you have viewed a file make sure you delete it from the documents section on your start menu!
when i was younger i used to create a folder, place everything in it and then under properties make it a hidden folder.
(to 'see' the folder simply change options to view hidden folders)
Very simple and effective, depends on how much your dad knows about computers though
plus that was on windows 95 i dunno what XP is like