Windows XP lost 1.1 percent of the operating system market in August, but it remains the dominant OS among end users.
XP accounted for 71.8% of all OSes used by the people who visited the 40,000-some sites that web measurement company Net Applications monitors for clients. Net Applications, which tracks the operating systems used by a pool of about 160 million unique Web site visitors.
But the decline was matched by significant, 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 licence customers and subscribers to its TechNet and MSDN services.
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.