Microsoft

Windows 8 may not be selling nearly as well as Microsoft projected, according to a report.

"Sales of Windows 8 PCs are well below Microsoft's internal projections and have been described inside the company as disappointing," Paul Thurrott wrote on his Supersite For Windows today, citing a source inside Microsoft.

The culprit? "Lackluster PC maker designs and availability," according to Thurrott.

But he lists plenty of other reasons too, including Windows 8 itself as "confusing" because of its mix of touch and a standard Windows 7 desktop.

And he cites the simultaneous release of Windows 8 Pro and Windows RT as problematic.

Though Windows 8 Pro can run older Windows software, Windows RT cannot, which "doesn't make a lick of sense," according to Thurrott.

Roger Kay, principal analyst at EndPoint Technologies, agrees. "The split between the Windows 8 Pro and RT versions makes the positioning of Windows 8 difficult," Kay said to CNET on Friday.

Kay continued: "The new touch interface is really fantastic for the high-mobility market, like tablets. But turn the whole world upside down for a few tablets?"

Microsoft, at least publicly, doesn't seem to agree with these assessments. CEO Steve Ballmer, speaking at the Churchill Club in Santa Clara, Calif., this week, said Windows is off to a spectacular start.

Related stories Microsoft has sold 4 million copies of Windows 8 since launch

And at Microsoft's Build conference last month, Ballmer boasted that 4 million copies had been sold in the few days since launch on October 26.

But there have been other reports about a lack of interest in upgrading to Windows 8.

While a general lack of immediate interest in a new operating system is not unusual, based on past Microsoft OS rollouts, the barrier may be higher this time because of the touch-centric interface, particularly at businesses, according to Kay.

Indeed, Windows 8 is spurring innovative hybrid designs, such as the HP Envy x2 and the Acer Aspire S7, which combine the traditional clamshell with touch screens. Consumers and businesses may take a while to fully embrace the new paradigm.

Kay did add that it will take a few months for retail stores to roll over all new PCs to Windows 8. So it won't be until January of next year that Windows 8 is fully represented at retail.

And sales of the Microsoft Surface tablet seem to be doing OK. Initially, the 32GB model was sold out for about a week.

Microsoft, when contacted, did not comment on the report.