Not many tips before Office 2003 is done as Office 2007 will be out in just a couple of weeks but I ran across this yesterday.
When you want to save the names and email addresses that autofill as you type in Outlook as you delete a profile or move someone to a new computer and are not using the files and setting transfer wizard then there is one file that you need to save.
Go to the C:\Documents and Settings\
The NK2 file is an encrypted, or at least not very readable file that can only be read correctly in Outlook but this is a great timesaver for many and I know people hate it when they have lost the autofill for their Outlook email addresses