If you know the features you want check out forummatrix.org, you'll be able to compare all the different community forum software

I used phpbb for several sites i've created and i'm pretty happy.A lot of resources on the net an a friendly support forum on their site.
Also know that it really easy to work with and install.

Thank you so much for your help!

I am starting a new forum, and am using vBulletin software. In the automotive community at least, it is probably the most widely-used forum software. You can get more information from their website: www.vbulletin.com

yeah VB is the most popular paid one, and PhpBB or something like that is the most popular opensource one.

IMHO VB is better in the long run

Out of the Open GNU GPL stuff, PHPBB or MYBB would probably be the best option. But I say again goto forummatrix.org

Most forum software provides an easy way for you to upgrade from a different forum software. However, sometimes it's not as clean as it could be and things break. Also, you might not get all features transferring over (private messages, for example).

I would splurge for a vBulletin license for $160.

If you do have a bit to invest and you are hoping to get it as big as daniweb you should be looking looking at vbulletin...that's pretty much the smartest choice, if you are hoping to start with as little expense as possible phpbb would be good, as dani said it's pretty easy to upgrade later, just export the foum db in your cp and import it into your new forum software

vbulletin is the best for building a forum. But if you are looking for free scripts, phbb is the most commonly used forum script.