The best place for a discussion web is in a subweb. Shared borders will
not work across subwebs. In your navigation in the main web add a link
to the "home" page in the discussion web.
If you are using FrontPage navigation components, add an external page
to the navigation view pointing at the "home" page for the discussion
web. On the discussion web add a link back to the home page (or some
other page) in your main web.
