What size resolution would you suggest for a dvd/game projector for an in home theater?

I would like to create an in home theater as a surprise for my husbands return home from overseas but I really do not know what to look for. I would like to use a projector to project dvds and possibly ps3 onto a 5 foot wide projection screen in a very dark room in my house, and the seating will be approximately 10 feet from the viewing screen. Any help would be greatly appreciated. Thankyou!