The headline is simple, 40 million copies sold. Wow, we rox0rz! This is twice as fast as the XP adoption rate. What he didn't mention is that sales of PCs have more than doubled since XP came out. Silly Vole, no statistical cookie.

The problem? Well, PCs sell at about 60 million units a quarter, and everyone we talk to expects sales of around 240-245 million units in 2007. Vista went on sale at the end of November for corporate customers, and one would expect a fair chunk of sales there from pent-up demand.

Well, maybe MS was just kidding about the 'Wow' stuff, the only part that floored me was the antagonistic licensing, crushing DRM, and borderline malware embedded. OK, so maybe the pent-up demand side is overblown.

In any case, there were corporate sales for over two months before release, and another two and a half months of true sales. Add in all the Vista free upgrade coupons that were cashed in, and you have a lot of sales outside the normal two and a half months' worth.

A few people are smart enough to avoid Vista, but most people are forced to buy it. Microsoft makes it very hard not to. In the end, you probably should have at least one copy of Vista sold per PC, quite possibly a little more.

So, you should be at about 20 million sales a month, for two and a half months, minus about five per cent for those smart enough to avoid the software, plus ten per cent for all the other non-bundled sales combined. I would guess that makes it (20 million by 2.5 by 1.05 = 52.5) around 50 million units sold.

Microsoft is now claiming 40 million units as a major win? Does anyone else sense something wrong?

It's a big number but not as big as it might be if the software was any good. µ