Have Microsoft sold 20m copies of Vista?

Many online sites, including the New York Times, are reporting Microsoft's claims that they have sold 20 million copies of Vista in its first month of full release (including pre-orders), supposedly twice the sales pace of Windows XP.

"It's a stronger-than-expected start," Bill Mannion, a director of product marketing for Windows, said.

However, there is a growing trend of sites doubting this information from the Redmond based software giant.

PC Magazine is particularly critical as the cite the reasons why they believe this is nonsense:

• Microsoft's sales period for the license sales is significantly longer than 30 days—more like four months.
• License sales into the channel do not correspond to actual Vista PC sales out of the channel.
• The numbers don't match up with real world PC sales volumes.

They also quote analysts, particularly focusing on the pre-sales nature of the claims:

"Clearly there haven't been 20 million PCs sold worldwide since Jan. 30, and we're really only talking about February," said Stephen Baker, NPD's vice president of industry analysis.