Paul;
Outlook itself holds objects in a file that is named, by default, outlook.pst. Remember that Outlook is simply a client, and not an email database/engine.
You can easily locate your PST file by doing a file search on your OS.
Keep in mind that the objects in a PST file maintain their security if you have an NTFS drive.
Hope this helps. If you need more information, please provide specifics.
Good luck!
~wmichael
"small change can often be found under seat cushions