.NET MVC Razor with forums

I am looking for a forum to add to my site. My site is being developed in .NET with C# MVC Razor.

My goal is to use the forums, but importantly, use the underlying functionality to build my user profiles upon. I would like to make use of friends, messaging and other services in a custom profile, so I need to be able to plug into these features and add/retrieve/remove data.

I have obviously looked into solutions based more around my sites platform, ie, MVCForum and Yet Another Forum, but have had a lot of trouble with integrating the memberships while using a CMS. For example, if I do my own custom site implementation and use the membership provided by the 3rd party forums (in my case MVCForum and YAF), this is possible. However, when I use a CMS like Orchard, I find that one membership fights another, making it near impossible to have an integrated membership system.

I'd like to use a CMS, like Orchard and so I would also like to have users sign into my site and also be signed into the forums. I don't want users to have to register twice (once on the site and once on the forums), nor do I want them to have to sign in twice.

Any advice would really be appreciated.