I recently happened to travel on a Lufthansa A340-600 between Frankfurt and Vancouver. I certainly appreciated the on-board passenger infotainment system: each passenger has his own touch LCD display with a selection of music, movies, and other information.
My first impression is the system is not very much responsive: maybe by design to avoid unwanted touches while moving to/from the seat or simply worn out (alarming for a quite new plane).
On my way back the system was irresponsive, I could not even turn it off, since apparently even the on/off button is part of the touch-screen. I asked to attendants and they kindly rebooted the system, so I could see the startup screen:
So it appears they are using Windows CE and loading the system image through a serial line.