Microsoft seem to have missed an option in outlook 2003 to rename profiles. You can give it a nice name upon adding or copying (but copying causes it to redownload all mail again, pain in the arse if you have a large mailbox)

So if you've got a few non-descript profiles like 'outlook' that need renaming this can be done easily via registry through the following keys.

HKEY_CURRENT_USER\SOFTWARE\MICROSOFT|WINDOWS
NT\CURRENTVERSION\WINDOWS MESSAGING SUBSYSTEM\PROFILES