This is really not as difficult as you think.
1. You install vbulletin.
2. You run the vb
impex script to import the photopost users
3. you flush the pp_usergroups table in phpmyadmin
4. you reinstall the gallery to integrate with vbulletin.
We offer this service for users whom do not want to do it. It is the photopost install service which is $59.00 and you can email us for a custom forum install which is $70.00. You will find vbulletin charges like $160.00 to install there product.