Yes, vb is not free and phpbb is free.
If you can afford a vb license, vb is the best. If you want free solution, go to www.opensourcecms.com/ and try those forums before install.
I would not take anything away from vbulletin. But what about the phpBB ver. 3.0? It's a definite improvement, but it's still not vbull. Any opinions on the new version?
Vbulletin is the right choice, just because of wider audience. I've opted for vbulletin over phpbb/ SMF, as the competitor & target audience are familiar with vbulletin navigation & style