<< >> Of course, this can only have the effect of replacing IE 6 with IE 7, it can't have any effect on the user share of IE 5 + 6 + 7. <<
talk about a dumb assed statement>>
Please explain what is dumb about it, stupid. Explain how Microsoft's Automatic Update pushing IE 7 to someone's Windows computer can have any other effect than replacing IE 5 or 6 with IE 7, so that the count of IE 5 + 6 is reduced by one while the count of IE 7 is increased by one, leaving the count of IE 5 + 6 + 7 absolutely unchanged, and incidentally leaving the count of PC's with Firefox installed unchanged.
I am fully aware that it is futile to ask this question, since, as far as I can tell, you have no idea what would constitute an explanation of anything.