The PS3 will need to sell around 20k in Japan this week to achieve 100k more than the Xbox, so it's unlikely. Nevertheless, the margin between them is significant and must be worrying for Microsoft.
While the PS3 is more expensive, I think that Blu Ray support is the crucial difference between them and a major factor for the higher sales. The improvement in PS3 sales since the end of the format war is noticable, especially in NA.







