Microsoft (MSFT) revealed earlier this week that sales of Windows 8 were outpacing its predecessor with more than 40 million licenses sold in a month. Despite the company’s latest milestone, U.S. sales of Windows devices have fallen 21% since last year. NPD Group reported the latest numbers, noting that sales of laptops, which have been weak throughout most of 2012, have fallen 24% year-over year while desktop sales dropped 9% from last year. While it is still too early to place the blame of a weak PC market on Windows 8, vice president of industry analysis at NPD Stephen Baker believes that the operating system “did not prove to be the impetus for a sales turnaround some had hoped for.”

A month after the launch of Windows 7 in 2009, the operating system was found on 83% of new PCs being sold. Windows 8, on the other hand, has captured only 58% of new computer sales. The research firm claims that Windows 8 tablet sales “have been almost non-existent” and represent less than 1% of all Windows 8 device sales to date, however the numbers are flawed because they do not include Surface tablet sales.

“The bad Back-to-School period left a lot of inventory in the channel, which had a real impact on the initial sell-through rates for Windows 8,” said Baker. “The strong performance of Windows 8 notebooks with touchscreens, where Windows 8 truly shines, offers some reason for optimism. These products accounted for 6 percent of Windows 8 notebook sales at an average price of $867 helping to re-establish a premium segment to the Windows consumer notebook market.”

One reason for the lackluster Windows 8 sales could be the price. The average selling price of Windows computers has “jumped significantly” from $433 to $477 in the past year.

“Windows 8 notebooks have seen a nearly $80 rise in selling prices versus the prior year, propelled by the aforementioned strong performance of touchscreen devices and a solid uptick in the pricing on mainstream notebooks,” the firm’s press release read. “Windows 8 desktop ASPs were also strong with selling prices up nearly 10 percent, driven by the same factors as notebook sales.”

Dan joins the BGR team as the Android Editor, covering all things relating to Google’s premiere operating system. His work has appeared on Fox News, Fox Business and Yahoo News, among other publications. When he isn’t testing the latest devices or apps, he can be found enjoying the sights and sounds of New York City.