Actually they are figures you totally made up. Only 3.4 million X360's were sold in the US at the end of Novemember. http://www.next-gen.biz/index.php?option=com_content&task=view&id=4362&Itemid=2
(See I actually provide valid info with links, unlike you) And if you think 1.7 million were sold in December you are absolutely crazy.
Are you sure you've been reading this thread? I posted links, and I'll do it again for you.
"Microsoftâs Xbox 360 is on track to reach our 2006 sales estimate of 4.5 million units in the U.S."
The 360 sold 610K in 2005 to the US per NPD.
That makes a total of 5.1 in the US per NPD. Argue with them if you disagree.
Sales for MS means selling to retailers. This is not what we count here.