Its going to be difficult moving the forum over to Drupal I think.
Pages (newsposts) and images Is not a problem I think, I just spent the last two weeks importing data from a custom ASP based CMS over to a fresh Drupal install and some parts are kinda tricky to import (most obvious comments and forum parts).
If you decide to go for Drupal check out the module 'Node Import' it will help you import pages from a CVS-file into Drupal without messing directly in the database.
Also, Drupal is not the most easy system to learn but its a good alternative for a future site IMHO.
