You should use phpBB. phpBB is the best forum available, IMO and best of all...it's free. If you can wait 'til sometime right before Xmas there will be a public release of Minverva which is a great modified phpBB board with tons of extra features. The url is
www.flexion.org. To install phpBB you can use MySQL 3x, MySQL 4x, PostGre, MS Access, MS SQL (Maybe?) but, for Minerva you can only use MySQL 3x or 4x for the time being. Other than that all you need is at least PHP 4 and a working webserver.