It depends what exactly you want. We don't have multiroom, but have a "magic eye" (bought from Tesco, installed by ourselves). This enables us to watch and control the sky from our kitchen as well as our living room, but the same thing must be shown in both rooms. We've buried the wire below the flooring and through the walls so no wires messing the place up! You can also get a wireless transmitter that will do something similar if it is not possible to link them like this.
If you want to watch different programmes in different rooms, as the others said, you will need multiroom