Windows 7 steals biggest chunk of share from XP

Microsoft's Windows ran to stay in place last month as Window 7's market share gains made up for the largest-ever declines in Windows XP and Vista, data released today by Web metrics firm Net Applications showed. But it was Microsoft's ability to retain its share in the face of record slumps in its older editions that was the news from Net Applications. By Net Applications' numbers, Windows 7's gains were primarily at the expense of Windows XP. For each copy of Vista replaced by Windows 7 during November, more than six copies of XP were swapped for the new OS. Meanwhile, Apple's Mac OS X lost share during November.

Even though Windows XP lost 1.45 percentage points to end November with a 69% share, and Vista fell 0.2 percentage points to 18.6%, Windows kept its total operating system share at 92.5%, the same as in October. For Vista, November marked the second time in three months that the often-maligned operating system lost share. The declines in XP and Vista were both records in Net Applications' tallies, which because of a change in methodology instituted last July go back only two years. That trend, if accurate, means that the 2007 operating system has peaked, and will now, like XP before it, begin a slow, inexorable decline as it is replaced by Windows 7. Give Windows 7 all the credit for holding Microsoft's line. Windows 7 has been on a share roll since it debuted, according to Net Applications.

In the first full month after its Oct. 22 public launch, Microsoft's newest operating system increased its share by 1.8 percentage points, ending November with 4%, more than enough to make up for the losses by XP and Vista. Less than three weeks after its release, Windows 7 had acquired a slice of the OS pie that it took Vista five months to reach. Currently, about three of every four Windows PCs runs XP, while one-in-five runs Vista. Neither XP nor Vista will vanish overnight if Net Applications' data is any indicator. Only about one in every 23 Windows systems is powered by Windows 7. Almost as unusual as Windows remaining in place was the Mac OS X's dip. Most months, Mac OS X gains ground on Microsoft, albeit by small margins: Over the last 12 months, Apple's OS has increased its share by an average of less than 0.1 percentage points.

By Net Applications' estimate, Apple's operating system finished November with 5.1%, a decline of 0.16 percentage points, the largest since February 2009 and only the third negative number this year. Linux, on the other hand, came up a winner last month, returning to the 1% share mark for the first time since July. It then weights share by the estimated size of each country's Internet population. Linux's all-time high in Net Applications' rankings was May 2009, when it nearly reached 1.2%. Net Applications measures operating system usage by tracking the machines that surf to the 40,000 sites it monitors for clients, which results in a pool of about 160 million unique visitors each month. November's operating system data can be found on Net Applications' site.