While Microsoft chief executive Steve Ballmer says the company has sold over 4 million Windows 8 upgrades since launch , data collected by Web analytics firm Net Applications suggests adoption of the new operating system is much slower than that of its Windows 7 predecessor.

Data collected during the week ending November 18 -- three weeks after the operating system's retail release -- puts Windows 8 usage at just 1.19 percent, behind not only Windows XP, Vista, and Windows 7, but also Mac OS X 10.8, 10.7, and 10.6, and even the underdog of operating systems, Linux.

Compared to Windows 7, the results are disappointingly slow. While Net Applications does not give us access to data going that far back, reports show that within a week of its release, Windows 7 had a market share of 2.15 percent.

Interest in Windows 7 was so strong that it managed an average of 1.91 percent for the part of October prior to its retail release.

The press and pundit reaction to Windows 8 has been mixed (to say the least). While there's no doubt that the operating system is just as fast as Windows 7 , and data suggests that it crashes far less than either Windows 7 and Windows XP , severe doubts have been raised about the new user interface that Microsoft has chosen for it, with usability experts branding it " confusing " and "disappointing" for "both novice and power users."

Combine this with the fact that it is hard to come up with a compelling reason for anyone to upgrade to Windows 8 -- at least just yet -- and we get an insight into why adoption might be slower this time around.

Another problem facing Windows 8 is the stagnant PC market. Microsoft is highly reliant on its hardware partners to get its operating systems into the hands of users, and right now, but with sales faltering as the entire industry feels the pressure from tablets and smartphones , Microsoft is turning to the upgrade market to help bolster sales, offering cut-priced deals to lure people to the new platform.

The research firm uses data captured from the 160 million unique visitors browsing some 40,000 Web sites it monitors for its clients.

Image source: Net Applications.