installing a forum

I'm looking to install a forum on our webserver and I'm having a hard time finding out what my options are. In FreeBSD you can goto www.freebsd.org/ports and get a good idea of what's available. Is there something like that for FC4? Initially I'd like to set it up so that people who have accounts on the server could use the same username/password to login to the forum. Now, if this is a good or bad idea, I'm not sure... I'd like to objectively hear what people have to say. Thanks

Here's one:

http://www.simplemachines.org/index.php

Here is another one;
http://www.punbb.org/
Forums are pretty easy to install. You will need php and mysql for most.Phpmyadmin makes it easier.Basically what I do is use phpmyadmin to create the database. Then upload or move the software to the server and follow the directions.The only tricky part is when you add the tables. I use phpmyadmin, go to the database, click on SQL then browse to the .sql file and import.Once you have done it a few times it is easy but the first time can be a little hard to figure it out.There is some good how to's around that explain it alot better than I can. Good Luck