The W5500 has 100Hz whereas the V5500 is only 50Hz, there may be other differences but that's the big one, this means that the W5500 has more input lag than the V5500, so it may not be the best choice for gaming. Not much will make your wii shine though to be honest, a decent CRT is probably still the best for that, although I don't know much about what the wii looks best on (I just know that it's the thing most people struggle to get a good picture with).
But seriously, to the OP, I can't think of a better £600 TV than the P37X10 for watching movies, only shy away if the room is very bright or you spend several hours on the xbox at a time