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That is a very tough area to put a photo in because of the way that menu stretches depending on how much you have pinned to the start menu or how many recent programs you have displayed.
You could try a resource hacker of some kind and open up the aero.msstyles and edit image number 808 and 809 if you are using the default Aero theme.
I would recommend you go to Virtual Customs
and ask there I know they know how to do it.