well it all depends. You already have a forum running with users. Your already had a photopost running with users. You would need to mesh these together. Unless of course your doing to dump photopost and do a new install
I created a script to import photopost users into a clean
vb forum
http://www.photopost.com/forum/showt...67#post1107167
But your not doing this so you would need to write a custom script to import the users with an incremented id.