Dear Karan.
I can still suggest Joomla/Fireboard which is customizable and scales well. Joomla is also LDAP capable and offers some nice features like FAQs, News Headings and so on. Fireboard currently works in compatibility mode on Joomla 1.5 but should do it's job either. I am personally well known with Joomla Templates.
If you are just looking for a forum, phpBB is very nice. There are also some Board/Portal attempts available for phpBB like Board3.
Fudforum does not scale so well and is AFAIK text based.
Simplemachines is also nice and there is a portal software available for it, too.
Best Regards Marcus