Microsoft bragged today that in the month since Vista's consumer version came out, it has sold 20 million copies--compared with the 17 million copies of XP in its first two months. That makes Vista twice as successful, Microsoft says.

Hold on. The company in January said Vista would sell five times as fast XP did in its first few months. Accounting for the 17-million-in-two-months XP sales, Vista would have had to sell some 42 million copies in its first four weeks. However, a couple of weeks into Vista's consumer launch in January, CEO Steve Ballmer abruptly lowered expectations, saying, "I think some of the Windows revenue forecasts in fiscal year ’08 I’ve seen are overly aggressive." (See the full story here).

In other words, Microsoft lowered expectations, then crowed about meeting them. (I assume. It doesn't seem as if Mr. Ballmer gave a new goal figure, but merely warned Vista wouldn't quite make his original projection.)

Still, Vista is far from failure. "We're encouraged by the strong debut. While it's very early in the product life cycle, we are setting a foundation for Windows Vista to become the fastest-adopted version of Windows ever," Kevin Kutz, director of Windows Client, said in an email forwarded to me.

 And in a recent story, Directions on Microsoft analyst Michael Cherry told me, “It really is time to get over the day-to-day death watch on Vista. ”

Let's wait for Vista's two-month anniversary to compare true figures.