Customize dashboard, registration and login features.

Hey.
What I’m trying to do is to sort of “disable” the dashboard for others other than the admins.

I’m building a community-ish site, and I don’t like the wordpress register and login pages.
I’d like to use wordpress more like a cms and not a platform, so for example: I’d like to disable the wordpress login/register pages, add custom ones that are linked with a forum so that people don’t have to register twice for the forums and the blog itself to comment and such.

However I haven’t found a way yet.
I’ve tried a few plugins but they either just add fields to the registration page or take it to a different location.

Have you got any tips for me? Are there any plugins I should try, or can you name a few php files I should look at.

If it wasn’t clear what I wanted please ask.