What about for a first timer with a low budget. Do you think phpbb will do the trick or will I get fucked with spam?
If you have to go the free route - I've been really happy with SMF - Simple Machines Forum - Home of SMF: Free PHP and MySQL forum software
It's really easy to upgrade, has mods, templates, and a user forum.
Make sure you have ImageMagick installed on the server, and change the default CAPTCHA settings in the backend (under options/images iirc)I really like vBulletin, I still get some spam. Worth $180 for sure.