Security concern in outlook 2002

Here's the situation

Environment
Outlook 2002/2003
Exchange 2003 Std. SP1


I have a user that logs in to the network on his laptop
the user (the president) is rarely at his desk (running around all over the plant)

He asked me to setup security on outlook to prevent people from view his email...I said sure..np...

How ever when I enable the logon using a password the previous mail is still available for viewing...infact you can cancel the login and view all the previous emails...the login just stops you from connection to the exchange server

Any ideas how i can lock down outlook or setup password entry on outlook

Yes I know the user should lock his PC when leaving his desk ... is there any other way to do this

how about have the screen saver lock the station?