Framework / platform for a .NET user group

Question

I am preparing the creation of a dot net user group. One of the step is to have a website to :

• Exchange and discuss between members, using a forum (or just a mailing list?).
• Share a common calendar
• Have a survey ready for its opening (asking people what they are expecting)
• Present activities to visitors
• Be a showcase for encouraging people to come.
• ...

As I am a SharePoint developper/trainer, my first thought was to use SharePoint. However, it is bad for forum, and customizing it (to make it a showcase) requires lot of work.

I looked over existing dot net groups. Lot of them are based on Dot net nuke. However, DNN seems a bit old-school. Am I right ?

Maybe a State of Art asp.net MVC application might be great. Using Orchard or Umbraco as a start might be a good solution. But they seem to lack community functionnalities...

If you were asked to create the Web site for a dot net user group, which framework/plateform/tool would you use ?