Mostly debian experience when it comes to MySQL and PHP, but I think I might know your problem. I use apache in linux, and in debian you can install all three of those programs and configure apache in less than 5 min. Anyway in linux you have to tell apache to recognize mysql and to support php extensions. Just a guess, but it sounds like you might not have all these things recognizing each other. Like a said though I don't use windows for web hosting, so I really can't help you too much.
BTW though, for you phpbb settings; most of those default settings should be fine. Make sure you set the MySQL and admin stuff up correctly, but besides that default settings should be fine.