The first factor that needs to be put completely to one side is picture quality. Unless you are a technology geek with a television the size of a multiplex cinema screen, there is no difference between the output of HD DVD and Blu-ray machines. Both offer high definition DVD playback superior to standard DVD players. Where Sony had the killer edge is that its Playstation 3 (PS3) computer games console comes pre-fitted with a Blu-ray player. So as Sony has sold 10.5 million PS3 consoles since it was launched in late 2006, that is 10.5 million Blu-ray machines already in...