vB on domain1.com and CMS (or blog) on domain2.com both using vB user database?

[ab420]

For simplicity, I'm calling these domains domain1.com and domain2.com...

I have a vB forum on domain1.com, and I am starting a blog on domain2.com, however I would like for this new blog to integrate with the user accounts of the forum on domain1.com.

I would really like to use Drupal for domain2.com, as I have used it before and I'm very comfortable using it, but so far the integration modules I found on Drupal.org integrate a forum right into Drupal on the same domain.

Is there any way to do what I'm trying to do or I am just crazy?

What if I get a vB 4.0 Publishing Suite for domain2.com, would I be able to do it then?

Would I have to upgrade my current forum to 4.0 to do that?

Is there another CMS or blog software I could use on domain2.com that would make this possible?

Thank you in advance for any help I get, I really want to make this happen, but I'm just not sure where to begin.