here's how: http://vgchartz.com/hwlaunch.php
ps3 is tracking above the 360. the 360 had a year head start - that means the 360 started selling a year before the ps3. that also means sales for the 360 should peak a year before the ps3. that means the 360 should stop selling a year before the ps3.
sure, the 360 is selling well in comparison to the ps3 at the moment but mark my words on the back end of this generation the ps3 will pass the 360's overall sales.








