So you have a new pc or a new Outlook profile. You login to your mailbox, all your data is there but your auto complete list which Outlook auto generates has gone, what a pain.
This is actually easy to get back and is basically just a file stored in your user profile on your pc.
Browse to :
C:\Documents and Settings\USERNAME\Application Data\Microsoft\Outlook
Look for a file called Outlook.NK2
The name might be different to that but will still have the same extension of .NK2
Copy or rename the file to it matches your Outlook profile name.

When creating meeting requests in shared calendars I found all users were getting replies (i.e acceptances or denies) when they were added as an attendee.

To stop this from happening the option is in quite an obscure place, at the following:

tools->options->delegates tab

In the list of delegates you need to select each one and click permissions, then UNTICK the delegate receives copies of meeting-relates messages sent to me

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