I think phpBB is the best forum script. You should download it.

My favorite forum software is phpBB. PhpBB is a high powered, fully scalable, and highly customizable Open Source bulletin board package (quote taken right from their web site). I found phpBB easy to install, stable and you can't argue with the price, it's free! There is a very active user community and it's easy to find add ons and customizations.
Demo : <URL SNIPPED>

SMF http://www.simplemachines.org/ is a good forum script. You can see list features of it: http://www.simplemachines.org/about/features.php . Hope you will find your favorite one.