I am in the process of ordering my first projector and screen but want to be certain I have got the right size screen for the projector and room. The projector is going to be fixed to the back wall of a room measuring 600cm x 340cm and will be aprox 220cm from the floor. I will be using a Gyrolock mount to fixe it to the wall rather than the ceiling . The screen (a DRH 231 x 130 16:9 manual) will be aprox 480cm away from the projector (a Sanyo Z2) The main viewing sofa ( ) will be aprox 380cm away from the screen. I have used a couple of online calculators to work this out and I 'think' I am going with the right size screen but just wanted to be double sure before I ordered it.