"Sales" is one thing, because all of the Microsoft employees and contractors have 'purchased' copies - at greater discounts. So unit sales can look extraordinary. Dollars won't be. And since activiations must occur during Installs, even "activation" numbers can look awfully potent.
One of our national clients had a 100-person regional office poised to change over, as a test case. Their central HQ did the regional manager and his 4 shift managers (& secretaries), then charged their hourly-rate for IT services, as a test case.
$20,000 later and the regional manager hit the ceiling, called it quits and the national client has backed up its forecast for a change-over to Win8 "for a long while". Admin costs, additional training plus all the additional hardware - some pretty hefty costs.
Oh well... that's why fishermen put little worms on their hooks. "All we need to do is get a nibble..."