Microsoft's Halo 3 is a monster. When it launched back in September, the game sold a whopping 3.3 million units in the U.S. More recently, Microsoft Corporate VP of Global Marketing Jeff Bell, revealed that Bungie's masterpiece had surpassed five million units sold worldwide.

A closer look at the data from The NPD Group through November shows that 4.1 million copies have been sold in the U.S. With 7.9 million Xbox 360s purchased in the U.S. to date, some simple math indicates that an impressive 52 percent of all Xbox 360 owners in America have picked up Halo 3.

That's an incredible attach rate and proof positive of the importance of the Halo brand to Microsoft and its Xbox business. Halo 3 has given Xbox 360 a huge lift in terms of console adoption. The Xbox 360 was the top selling console in September with over 527K units sold.

"The power of Halo 3 is quite evident," NPD industry analyst Anita Frazier commented to GameDaily BIZ. "Even more than the attach rate of the game, which is significant, the fact that when it released it drove hardware sales substantially is evidence of the power of the franchise. That is why content is so important - a really killer game drives hardware adoption more than any other factor (including price cuts)."

For comparison's sake (although it's not entirely fair since Halo 3's been on the market three months), Nintendo's Super Mario Galaxy has sold 1.12 million units in the U.S., and thus far six million Wiis have been sold, resulting in an attach rate of 18.7 percent.