Image quality from a projector is best in a dark room. When there's light to interfere with the projector's image, it takes a brighter output from the projector to retain a vibrant picture [source: Projector Central]. Besides, what kind of movie theater shows films in a half-lit room? Your home theater should be as dark as you can make it, and that might involve putting in some work with the windows and doors in the room. Ideally, the room would be entirely devoid of windows, but curtains can solve the issue of light coming in from the outdoors.
Buy some thick, heavy curtains that will block out all incoming light and establish a color scheme for your home theater. Forget boring white walls -- if you purchased acoustic paneling, paint the walls a color that matches the soft acoustic material. Your primary concern with painting the room is to use a flat, neutral color. This will limit the amount of light reflected by the walls and ceiling, and dark colors will help the room fade away and allow you to see nothing but the screen [source: Boylan]. While you're buying window curtains, consider adding one more luxury: a velvet curtain for the movie screen to lend the room a little theatrical flair.