"I visited Redmond, Wash., this week to talk to a few folks for my book.
Microsoft is disappointed that it can’t get more units of the Xbox 360 into the market. Various folks tell me it isn’t a problem with chip yields. I think it’s more of a systems issue, when the boxes come together. They’re working on getting more units out.
More likely, they will start catching up with demand for consoles starting in January. NPD Group estimated that Microsoft sold about 326,000 units of consoles in the U.S. and that it sold 1.3 million games. Microsoft said those estimates were a little low but wouldn’t say the exact number." [link]