phpBB would certainly be a good solution.
Also.... and this is cheating a little .... I'm sure that dream weaver can help you out with creating secure logins. It's been a while but I'm sure we did some kind of secure login where I used to work.
It also isn't too difficult to create a secure login.
My understanding is that you basically just query a database for the username and check that the password matches with the one provided. Then you could just use sessions to keep the user authenticated.
Also could have a failed login attempts column to catch potential hackers by having a maximum number of failed trys allowed before locking them out.
Remember if you are storing passwords in the database to use secure hash algorithm for encryption. This will add to the security.
Good Luck
