Chicago (IL) – Earlier today, we reported that Microsoft’s Internet Explorer has dropped below 70% for the first time nearly nine years. Even worse, market research firm Net Applications now estimates Microsoft’s Windows market share at less than 90%, which is still an impressive number, but a lower level than most PC users may remember. We had to go back to Windows 3.11 to find similar market share data.   

Any product that owns close to 90% of a market that is as gigantic as the global PC market would be considered a huge success. In the case of Microsoft, that is, of course, different. Windows has suffered from a continued market share decline since the 2003/2004 time frame and November 2008 was the first month in a very long time that Microsoft has dropped below 90%, 89.62% to be exact, according to Net Applications.

Net Applications has been providing operating system market share data since October 2004 and estimated Windows’ market share at about 96.4% at that time. In November 2005, Windows was down to 95.5%, in November 2006 to 94.2% and in November 2007 to 92.4%. Over the past twelve months, Windows lost 2.8 points of market share, more than in any other year in the operating system’s 23-year history (Windows 1.0 was released in November 1985.)

Windows market share is generally believed to have peaked at 97.5% in the 2002-2003 time frame. Of course, we were interested in finding out about the timeframe when Windows crossed the 90% market share mark on the way up. It turned out that we had to go back quite a bit and if we believe this story published in December 2005 by Ars Technica, then Microsoft cleared the 90% hurdle in 1993 or 1994 with Windows 3.11. On a personal note, this is about the time when this author was first confronted with a Windows PC and was fascinated by the simplicity of the operating system (well, at least from the view of the time back then.)

If we dive a bit deeper in the most recent operating system market share developments, then it is interesting to see that while Vista is now listed with a market share of nearly 20.5%, it is far from being able to pick up the market share older Windows versions are losing. For example, Windows XP lost about 2.4 points (from 68.67% to 66.31%) over the past three months, but Vista gained only 2.1 points (18.33% to 20.45%). And we are talking only about XP here: Windows 2000 lost an additional 0.35 points, Windows NT 0.03 points, Windows 98 0.05 points and Windows Me 0.02 points, according to Net Applications.        

Of course, the market share loss benefits other operating systems, especially Mac OS X and Linux. Net Applications estimates that Apple’s Mac OS X now holds 8.87%, up from 6.80% in November of last year and up from 3.2% in November 2004. Linux is listed with a 0.83% share, which is up from 0.57% one year ago. In November 2004, Linux’ market share was estimated at 0.30%.