Reinstalling would certainly help remove all the extra Registry entries for the domains and workgroups. If you do that, you can save the .pst files and Import them into the new profile, Outlook will create, once it has been reinstalled and started.
If you have not tried Importing the Personal Folders (.pst file) into a
new Personal Folders (.pst file), you might try that first.
Be sure to make the new Personal Folders (.pst file) the new
Default Delivery Location, in Outlook 2007, restart Outlook 2007 for the changes to take effect.
Then Import the original Personal Folders into the new Personal Folders.
The size of the .pst files do not sound out of line for Outlook 2007.
Let us know what you decide.
