Hi noyce
The easist way to sound deaden your ceiling is to use a suspended frame type, and fill it will the acoustic foam black tiles etc.
I wouldn't carpet the walls though.
You could make vertical slabs made from fabric covered foam sheets etc.
The advantage of the suspened ceiling is easy projector and cable installation.
Have a look here at my Yahoo installation pictures for some ideas!
Click here
The picture below is my ceiling with black felt tiles, with white tiles edging to allow the use of coloured uplighters etc.