From your experiences, is there any advantage of one over the other, or onebeing more difficult to configure/maintain than the other?
I can only speak about MySQL, as I haven't had any experience with PostgreSQL. I learned MySQL first since my host provider supports it, and doesn't support PostgreSQL. I'm not necessarily a cheerleader for MySQL -- it's just the first DBMS tool that I learned, and I've decided to stick with it for the tasks that I have requiring a database. (But I'm that way about a lot things <grin>: I've stuck with the "first one I learned" with these as well: Gnome, Emacs!)
I think you'll find strong supporters of both DBMS on this list. It may simply depend on your needs. If your needs are db-backed websites, then perhaps MySQL and its speed will suit you just fine. I believe you originally mentioned needing to develop a phpBB site -- MySQL will be fine for that job.
-- Clint <clint@xxxxxxxxxxxxxxxxxxxx>