Since November 2005, Microsoft has sold only 600,000 Xbox 360 unites in the United States. The data comes from the NDP Group which measures and projects nearly two-thirds of all US retail sales.
“The Xbox 360 debuted to much fanfare on November 22 in North America, where the unit has been in short supply. Analysts, video game publishers and retailers have said shipments during the key holiday season fell short of expectations.”
It has already been reported that partially because of how the system has been selling in Asia, Microsoft dropped its ninety day target of three million consoles, and is now hoping for a much more reasonable four and half to five and a half million sold by June 30th of this year.
Source: Joystiq