Limiting members to an external database

[Killkenny]

Hi,

I'm sorry if this has been asked before. I did a search and came up with nothing.

I am building a site for a committee of engineers and they want a forum on the site, so I figured the natural choice would be vBulletin.

The problem comes in where they only want their members to join the forum to post etc, but they want the general public to see the threads, but not contribute.

Is there any way I could limit the registration process to only members of the committee by maybe checking a unique number(like an ID number) against their existing database which will be sitting on the same server as the copy of vBulletin.

Any help would be appreciated.

Regards,
Kenneth