I would concur - logging in and seeing new posts in the various forums is great, finding that they're all 'Shakira' movies or other junk is a huge annoyance at best. Realizing that you'll never keep them all out, perhaps only allowing registered users to post would be a good start.
While we're on the subject, can someone go in and remove the obvious spam messages? I'd hate for a kid to come to the forum for assistance and be subjected to the nonsense messages.
Tom