For anyone migrating a Movable Type installation from one server to another, and having problems with incompatible dbm formats, here is the document that you need to read.
Migration of a Movable Type Installation
Published inTechnology
The path less traveled.
I also just moved my MT install from one host to another. I used the doc you referenced and also found this one to be tremendously helpful:
http://www.elise.com/mt/archives/000255moving_your_mt_blogs_to_a_new_server_or_web_host.php
They both were life savers.
Erik