Question, Does the 360 have both HDMI and component? I know the PS3 does. If so, why not go the cheap way out?
With the PS3 in the bedroom, wire the HDMI signal to the livingroom TV, and the component signal to the bedroom TV.
With the 360 in the livingroom, wire the HDMI signal to the bedroom, and the component signal to the livingroom.
Doing this, all you would need to buy is the cables, and pop a hole in the wall joining the 2 TV's
This would be your cheapest way out, and all you would have to do it toogle back and forth on your TV inputs. Neither machine can opperate both signals at the same time(HDMI and component).