I would go with InvisionBoard (http://www.invisionboard.com). I am in the process of setting up a bulleting board myself and I did try phpbb. I had problems during the initial install and had asked for assistance on the phpbb forums. I know since I didn't pay for support, nobody has to help me, but that is what happened. Plus, all I read about on the phpbb forum was about people having problems. I then tried InvisionBoard and even I, a novice at this type of thing, had it installed and working in less than 15 minutes. Lately, I just haven't had the time to write everything for it and open it up. Hopefully, that will happen soon.
This is just my opinion, though. There are obviously a ton of people out there using phpbb and other free boards just fine. I prefer InvisionBoard hands down.