Maybe people are actually starting to tire of Microsoft's eight-year-old Windows XP.
According to Web measurement company Net Applications, which tracks the operating systems used by a pool of about 160 million unique Web site visitors, Windows XP's share of the OS usage market fell 1.1 percentage points during August, tying its November 2008 record drop.
Windows XP's fall doesn't mean that the aged operating system is less than dominant: It accounted for 71.8% of all OSes used by the people who visited the 40,000-some sites that Net Applications monitors for clients.
But the record decline was matched by near-record, or record, increases in the usage share of Windows Vista, XP's 2007 successor, and the not-yet-officially-released Windows 7.
Vista's share climbed 0.9 of a percentage point last month, ending August with an 18.8% share, an all-time high. August's jump was the largest for Vista since June 2008, when it gained a full percentage point of share.
Windows 7, meanwhile, increased by 0.3 of a percentage point to close the month at 1.2%, the first time the unreleased operating system has broken the 1% mark.
Windows 7's share has more than doubled since May, when Microsoft issued the Release Candidate (RC), the final public preview of the OS. Since then, Microsoft has wrapped up Windows 7, and delivered a RTM (release to manufacturing) build to computer makers, volume license customers and subscribers to its TechNet and MSDN services.
The new operating system is slated to go on sale Oct. 22.
Overall, Windows gained a statistically-insignificant 0.02 of a percentage point in August compared to the month before. Together, all versions of Windows accounted for approximately 93% of the operating systems running machines that connected to the Internet last month.
Apple's Mac OS X, on the other hand, remained stalled -- it gained a mere 0.01 point -- to end August as it did July, with a 4.9% share.
Starting with July's data, Net Applications changed its counting methodology, and for the first time weighted browser share by the estimated size of each country's Internet population. That nearly halved Mac OS X's share, dumping it under the 5% bar, while increasing Windows XP's share as it reduced Vista's.
"That makes sense," said Vince Vizzaccaro, Net Applications executive vice president of marketing, last month in an interview. "Now we're giving more weight to countries that are behind, technology-wise."
According to Net Applications, countries such as China, Brazil and India were underrepresented in its previous calculations, while others, like the U.S., were over-represented in its tallies.
The decline of Windows XP was also reflected in Net Applications' browser share data. Internet Explorer 6 (IE6), which remains XP's default browser, lost 2.4 percentage points of market share in August, for instance.
Net Applications' operating system data can be found on the company's site.