I'm planing on adding onto my house in the next year to make a toy room for myself.

The idea is to move my 2 channel setup (no sub), a projector and a 120 inch screen, 3 chairs and thats it. Given those assumptions, what size should the room be, should the equipment be placed on the long side, or the short side of the room.. any ideas for dirt cheap wall treatments, I was thinking about maybe strips of carpet on the walls, kind of like elvis's setup.. not sure how that would work though and I know the wife would hate it.

Ideas and other thoughts are welcome