Microsoft Corp says it has sold 20 million copies of Windows Vista in the first month of its release.
This means the new operating system sold twice as fast as Windows XP, the company said. XP, released in late 2001, sold 17 million copies in its first two months of availability.
The number includes copies licensed to PC makers as well as boxed copies of upgrades and the full OS sold in stores and online, so the milestone may not fully reflect actual end-user demand.
The market for new PCs grew about 80% between 2002 and 2006, according to Gartner numbers.