Xbox 360 NPD and our attach ratios are vastly different: Explanations?

[FreeTalkLive]

Some of the difference is that 1-2 games come with most Xbox 360s. That should bring the NPD ratio somewhere above 9. I have the Arcade and it came with 1 disc game and 6 XBLA games. However, most Xbox 360s sold over the holiday season came with 2 disc games.