PHPBB is relatively easy to configure, and works well. Many Hosting companies, like Godaddy will install all the necessary backend components. All you would have to do is tell them where you want them to install it eg. www.yoursite.com/forum.
Well actually my dad is trying to install it and I am helping (as little as possible)...that might be over his head...and take up more time then i'd like to donate hehe