One inexpensive screen (I have used) is a white board or a sheet of melamine, works pretty good...
thanks don. btw, i'm buying james' dell projector since he's got to upgrade. i know he built his own screen so i'm open for suggestions. should get the projector next week but finances will preclude any type of screen until, at least, late spetember. but i do have white, semi-gloss paint on my walls so it will work in a pinch!