Windows 8 just arrived last Friday, but already Microsoft is claiming four million upgrades to the new OS have been sold. Microsoft's new OS features a pretty nice upgrade price of only $39.99 for Windows 8 Pro, or $14.99 if you purchased a Windows 7 PC after June 2, 2012. Now, the four million number is only counting consumers and not enterprises that typically have volume licenses for an immediate upgrade, which could account for a larger amount. The number is also only for downloaded copies of W8 as retail numbers are not yet available, and neither is a direct comparison to previous Windows' versions. Still, Microsoft was not too eager to announce adoption numbers after Windows 7 launched, so maybe the tide is turning. At least in terms of upgrades that is, as the number of users on preview builds and RTM copies of W8 were five times smaller than the number for W7 before the official launch.