On the face of it, this graphic is correct ... user adoption of Mac OS X 'Lion' 10.7 was indeed much faster than that of Windows 7.
Cook claimed 'It took Windows 7 20 weeks to reach what it took Lion 2 weeks to get to in terms of install base,' and that Lion was downloaded 6 million times.
But that's where the 'correctness' of the graphic ends.
See, user adoption is just one metric, and in this case it's not the most important one, and I think Apple knows that. The metric that matters is users. Mac OS X might have been downloaded 6 million times, but Microsoft has sold over 400 million Windows 7 licenses.