I'm another Wordpress fan for blogging.
I've got to choose a forum option myself soon. I'm not sure bbpress bbPress » Home is the go which is by the wordpress guys. I like that it has tagging but there's other things I don't like, however if the wordpress crew are developing it I have high hopes. Else there's phpbb phpBB • Creating Communities Worldwide which has had a bad history of hacks but the latest version looks good, or maybe simple machines forum SMF Home of SMF: Free PHP and MySQL forum software
all of these are free