This should give you an idea of what to expect during next month's NPD figures: it's been announced that in the first 24 hours on sale, Modern Warfare 2 sold 1.2 million units in the United Kingdom.
Seeing as almost any other game on the planet would take 1.2 million as a great worldwide figure, for a month, for Modern Warfare 2 to have managed it in a single country over a 24 hour period speaks volumes as to how much cash is flowing into Activision HQ right now.