Dive summary:

• Microsoft launched Windows 8 on Oct. 26 and has spent $1.5 billion to promote the new operating system.
• NPD Group found that sales of Windows devices is down 21% in the four weeks after Oct. 26 compared to the same period in 2011.
• Devices that use Windows 8 were just 58% of Windows devices sold in the product’s first four weeks, and that does not compare well to 83% of Windows devices having Windows 7 in the four weeks after Windows 7 launched in 2009.

From the article:

… The ads are helping boost Windows' brand perception. In early November, it reached its highest point since the introduction of Windows 7 in October 2009, according to research firm YouGov's Buzz Score. That's a good start, but the software giant will have to continue to spend to keep its perception high and brand top-of-mind, because software purchasing often has a long lead cycle, built around when consumers or businesses need to upgrade, not necessarily when new operating systems come out. …