first week ending: 24 march 2007 (european ps3 launch)
last week ending: 21 march 2009
ps3: 19,249,584: http://vgchartz.com/hwtable.php?cons[]=PS3®[]=Total&start=39166&end=39894
X360: 20,356,841: http://vgchartz.com/hwtable.php?cons[]=X360®[]=Total&start=39166&end=39894