Windows XP's decline has accelerated and the decade-old operating system shed its largest ever chunk of market share in October, according to data from a Web measurement company.
The drop in XP's usage share, said Net Applications, was almost matched by an increase in Windows 7, which now powers more than one-in-three personal computers worldwide.
Windows XP plummeted by 2.5 percentage points in October, falling to 48%, a new low for the aging OS. Meanwhile, Windows 7's share jumped by 2.2 points to end the month at 34.6%.
XP has lost an unprecedented 4.4 percentage points in the last two months, or more than 7% of the total share it had at the end of August.
The quickened pace of XP's decline may hint that users have gotten the message that Microsoft has been mouthing for months: The 2001 software should be put out to pasture.
In July, Microsoft told customers it was "time to move on" from XP, reminding everyone that the OS had less than three years left in its support lifespan. Earlier this year, executives on the Internet Explorer (IE) team dismissed XP as the "lowest common denominator" as they explained why it wouldn't run IE9, or any browsers released in the future.
Then last month, as Microsoft quietly celebrated the 10th anniversary of XP's Oct. 25, 2001, on-sale date, the company touted the motto "Standing still is falling behind" to promote Windows 7 and demote XP.
The message has gotten through to most enterprises, said Michael Silver, an analyst with Gartner Research, in a recent interview.
"We estimate that 10% of organizations are done [with their migration to Windows 7], 55% are well on their way, 25% have just started or are starting, and 10% are pretty much nowhere," said Silver. "They don't see the urgency or haven't done much of anything to prepare."
The deadline for ditching Windows XP is in April 2014, when Microsoft stops patching the operating system.
"Enterprises don't want to run an OS when there's no security fixes," Silver explained.
Silver rejected the idea that Microsoft would extend the end-of-life date for Windows XP to please the 10% who have no plans to leave the OS. "Microsoft would be worried that that would just make users want to stay on XP a little longer," he said. "The longer they let them run XP, the more enterprises will slow down their migration."
Complicating the pending demise of XP and the rise of Windows 7 is that Microsoft is already talking about the latter's successor, Windows 8.
Like other analysts, Silver is not optimistic about Windows 8's chances in the enterprise, if only because most have just moved, or are in the process of moving, to Windows 7. As he has before, Silver again cited "upgrade fatigue" as one reason for Windows 8's likely poor reception by corporations, and the consumer focus of the unreleased operating system as another.
Unmentioned by Microsoft in all the hubbub around XP and Windows 7 is Vista, the hapless operating system that debuted in early 2007.
According to Net Applications, Vista accounted for just 8.9% of all operating systems last month, down a percentage point in the last three months and off 4.5 points in the last year.
Vista never cracked the 20% mark by Net Applications' measurements, peaking at 19.1% in October 2009, the same month Windows 7 launched.
Net Applications calculates operating system usage share with data obtained from more than 160 million unique visitors who browse 40,000 Web sites that the company monitors for clients. More operating system stats can be found on the company's site.
Gregg Keizer covers Microsoft, security issues, Apple, Web browsers and general technology breaking news for Computerworld. Follow Gregg on Twitter at @gkeizer, on Google+ or subscribe to Gregg's RSS feed . His e-mail address is email@example.com.