forums inside blog environment?

Just wondering if it is possible to put a forum inside wordpress/mu. I was thinking of using the main blog as the jumping off point for the community of bloggers. We have a sidebar on both sides and the content in the middle (header and footer too) and I would like to have the forums in the middle section - keeping the wrap the same so members would feel they are in the same place. The forums would be for bloggers to share questions and network - and the forums would not be available to everyone with a blog, just one space for everyone to come.

Is this possible with wordpress mu? I have read about vbulletin, bbpress and simple forums but I am not sure if it is possible to tie the two together - or make it look like it. I could install a single version of wordpress if it was possible but not with wordpress mu - and use the theme from my main blog.

I am totally confused - it seems like vbulletin and bbpress are stand alone installs that I would have to make look like my blog and simple forums is a plugin but I am not sure if the top and sides would stay intact.

Can anyone offer me any advice or direction where I can figure this out for myself?

Thanks!
Helen