What OS is he running?
If he is running XP or Vista, you can slip into his office on a weekend with something like ophcrack and it can tell you the password to his computer based on the password hashes:
Ophcrack
You can download the live CD and burn it (You can do this by downloading the .iso file and using a program such as CDBurnerXP.) It's pretty easy to navigate the menus.
After you figure out the password to his computer you should easily be able to access outlook and possible backup his .pst files if you find something dirty.