WordPress MU

I have looked everywhere for an answer on this with no luck. I think I might be overthinking the problem - and wordpressMU is a little bit of overkill on this.
I want 1 parent blog where users can sign up and create their own blog - all of the blogs - parent and child blogs will look the same. Users will not be able to change themes and widgets.

Is wordpressMU overkill for this. Should I just use a regular wordpress install with multiple authors and restrict which authors are displayed on home page?

If wordpressMU is the right tool for the job - any idea where I can find a tutorial for a simple set up to get to what I have described above.
Other posts have suggested the menus plugin http://wpmudevorg.wordpress.com/project/Menus - I see how that can help - what do I need to do so that every blog has the same theme?

simply do not allow more than one theme to be used and set that up to be the default theme!?

someone answered him in another thread where he pasted the exact same text.

Thanks - I didn't remeber that I had asked this on another thread. Sorry about that. Here is the link to the other thread - http://mu.wordpress.org/forums/topic/16235?replies=24