What is best forum script available to integrate with wordpress?

[Viruthagiri]

Ok i have a wordpress site network. I would like to setup a support forum for my site. But i don’t want users to signup in different pages. I mean i want my users to use the same wordpress login credentials in forum too. Is there any forum plugin available there. Thanks
PS: Is it possible using bbpress?

[Samuel B]

http://simple-press.com/

[Andrea Rennick]

bbpress is a forum plugin for wordpress, yes. and either one your users will not have to sign up again.

[John James Jacoby]

It is possible to do with either bbPress or BuddyPress, depending on the depth of integration and socializing you want your site users to have.