Add Discussion Board to Existing Site

We already have the website ready to launch. We are without a discussion forum for our users to use. I need a fast script of a discussion board implemented to our site, so that when user signs in to main area of our site , they also are signed into the discussion area also. NO SEPERATE LOG IN'S for the discussion area. I like the design of [login to view URL] . All areas including ad areas. I would control categories and all other standard forum features from backend etc. If service provider proves to be a quality informative team player, we have many projects that need started asap that they will be given. No bad coders or communicators!