There are several questions to ask before I can given an answer.
First, is he looking for a fixed screen or a roll down one?
Second, aspect ration. I am assuming 16:9
Third, is the room dark? If so a white screen, otherwise gray.
Fourth: Approximate room size, seating distance and projector distance from screen
Finally: type of projector.
If I make the most common assumptions where he is sitting about 10' away and the projector is 12-15' away, I'd look into a 110-120" screen. I would assume a fixed screen and that the room can be made dark. Also assuming he is using an entry projector like the Epson 8350 or the Mitsu 4000.
Under those circumstances, I would suggest he look for either the Jamestown screen, or the Elite SableFrame series. The Jamestown sells on ebay or you can order directly from
Home Theatre Projection Screens - Jamestown Home Theater Screen
The elites can be found in lots of locations, including Amazon and Sears, which usually has a very competitive price. General info can be found here:
SableFrame Series
Elite also makes cheap retractable screens, but once you get into that area, you get more questions like Electric or manual? and Tab Tensioned?