Back in Jan 2009: Aaron Greenberg interview
http://kotaku.com/#!5127839/microsofts-aaron-greenberg-talks-ces-xbox-360-in-09-and-beyond
Q. Microsoft recently claimed 17 million Live users and 28 million Xbox 360s sold...
Greenberg: Active users.
Q. Active. So what's the total of Live members that you've accumulated?
Greenberg: Uh... A significantly larger number than 17 million. To be clear, we are pretty conservative on how we report our members. It is active members — you have to own an Xbox 360 and if you're not active in the last six months, we recycle the gamertag and we remove your account. It is a true number of the people we have on the service.
I think it's important to note, if you compare those to PSN, those numbers you can have just a PSP, you can create an account on the Web. We don't count Web accounts.
You're an active member on PSN until you cancel an account. So, essentially forever. It's definitely apples to oranges when you compare those numbers.
