Projector & screen
A projector can output a display ranging from 30-300 inch diagonally, depending on the distance at which it is kept from the wall. So, the projector will depend on the size of your room. As the resolution plays an important part, go for a full HD projector if you have the money. Epson offers large range of 2D and 3D projectors. Live demos available too.
The surface on which you project also matters. Ideally, you should use a screen built for this purpose rather than a white wall as it's hard to get a perfectly smooth wall and the screen will show more accurate colours with better brightness. You can choose different screen sizes and types (higher reflectance, motorised or manual, etc), depending on the budget and space available.