I'm assumming a single machine here with an Outlook client that does not involve Exchange.
When I upgraded my home machine from XP / Office 2003 --> Win 7 / Office 2010, I unfortunately noticed that many of the outlook settings and configurations were not contained in the PST file. I extracted this information from the user registry used in XP and imported them into the Win 7 registry. My settings basically came back.
My specific concern centered because I use my outlook client to access many different mailboxes on different machines. But this did the trick and I did not have to go through the effort of manually adding (much less remembering what I had done before).
In your case, find the specific area in the users' registry, save it, do the update.
BTW, I recently upgraded inplace from 2003 ---> 2010 at work and all my settings survived and were properly converted.