moving Directory trees to existing directories

[taipan]

I am running outlook 2007 sp2 on windows xp 32 bit system and I'm wondering
if there is a way to do this.

We migrated from groupwise to MS Exchange 2007 about 6 months ago and most
of us are still new to Outlook 2007. I have a user that has 2 large directory
trees and we will call them Old and New. The old Directory tree contains a
lot of folders and emails from Groupwise and the new Directory tree contains
a mixed amount of emails from groupwise and recent emails from exchange. And
Both Email structures have folders with the exact same names.

Is there a way they can combined all of their emails together into one
directory tree maintaining the tree structure but having the emails from both
trees located in their respective folders.

I know this can be manually if one went to each folder and did the brute
strength way of moving all of the emails. Is there an easier way or a third
party software that can do this? If there are duplicate emails I can deal
with this, I have software that will sort the emails and move duplicate
emails into a different folder.

Thank you for the help.