As the title stating all that , I am running with a Japanese C2D MacBook, that indicates it contains a Japanese keyboard. From OS X, it goes 100% fine without any issues .
However,from Windows XP SP2, Bootcamp 1.2, all windows updates, it is recognized / used as the US keyboard. For example., when you keep the shift in your hand and issue the number 2, on a Japanese keyboard then it must be displayed as " but it is getting displayed as @ that is the same as on a US keyboard. This is not looking as a big issue here as I am used to a US keyboard anyway, but there are some different buttons which don't work, but should.