Online Forums

Hi,
I am trying really hard to find a decent forum creation tool that does'nt
require me to be a rocket scientist !!!
It's for a sixth form college website, so I can't use many free online
providers because of the adverts and links.
The biggest issue is that we need to create a predefined list of users based
on thier network logins so as to assure accountability. No nicknames or odd
handles!
Any ideas anybody I'm pulling my hair out on this one!

Thanks

Stu:confused;