Microsoft representatives are citing retailer reports that over 60 percent of GTA IV copies sold in the US are Xbox 360 versions.
Gamerscoreblog, run by Microsoft staff and citing "data from the US team", wrote, "According to retailers more than 60% of all GTA games sold in the first week were the Xbox 360 version."
The site also says that Xbox 360 hardware sales rose 54 percent week-on-week, while 40 percent of new consoles sold were bought along with a copy of the game.
The stats come a day after Microsoft declared victory in Europe, citing Chart-Track's reports that 100,000 or so more copies of GTA IV were sold on 360 than on the rival PS3.
Gamerscoreblog also reels off some Xbox 360-specific gameplay stats, revealing that 2.3 million people went online with GTA IV in week one, over 12 million GTA IV Achievements have been unlocked (for over 100 million Gamerscore points), and that the average gamer spent more than four hours playing it while hooked up to Xbox Live in week one, which is a new record.
All of this helped Xbox Live achieve 1 million concurrent users over the weekend, and unsurprisingly this has propelled GTA IV to the top of the Xbox Live gameplay charts, finally toppling Call of Duty 4.