Windows XP lost 1.1 per cent of the operating system (OS) market in August, but it remains the dominant OS among end users.

XP accounted for 71.8 per cent of all operating systems used by the people who visited over 40,000 web sites measured by Net Applications. Net Applications, 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, the XP successor launched in 2007, and the not-yet-officially-released Windows 7.

The Vista share climbed 0.9 of a percentage point last month, ending August with an 18.8 per cent 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 per cent, the first time the unreleased operating system has broken the 1 per cent mark.

The Windows 7 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 per cent of the operating systems running machines that connected to the Internet last month.