Phorum's developers pride themselves on creating message board software that is designed to meet different needs of different web sites while not sacrificing performance or features. You can get PHP from the PHP site or if you are leasing web space, your provider may already have it installed. As database there is currently only MySQL supported while it should be possible to port the database layer to other databases. MySQL is available from MySQL AB. It is OpenSource. Just download, decompress, configure and go.