The figures for August 2012 show Windows on 91.77%, OS X on 7.13%, and Linux on 1.10%
And despite all the talk about iOS losing market share to Android, that's not showing up in terms of web usage.
The iOS web share was 65.94% in August 2012, continuing the upward trajectory that NetMarketShare has been reporting all year, apart from a slight dip in March.
Android rose to 20.93% from 20.16% in July.
The biggest loser is Java ME (down from 19.19% in January to 8.37% in August), reflecting the rapid shift from feature phones to smartphones.
Also recording falls are BlackBerry (2.59% in January, 1.90% in August) and Symbian (falling from 5.20% to 1.44%).
StatCounter paints a different picture of the mobile world, reporting that Android continues to be the most used OS on 28.21%, ahead of iOS's 24.48%.
The difference can be explained by the fact that the two service's figures reflect visits to two separate groups of web sites - those for which StatCounter provides analytics, and those which use Net Applications' similar service.
Page 2: Browser shares
Browser share trends are generally flat.
On the desktop, Internet Explorer still accounts for just over half of the traffic recorded by NetMarketShare, with Firefox and Chrome taking approximately one-fifth each.
Safari's and Opera's are also fairly static at around 5% and 1.5% respectively.
Opera Mini's share continues to shrink (now 8.59%), and both Firefox for mobiles and Internet Explorer for Windows Phone are stuck in the 'other' category (2.76% in August).
StatCounter's figures for browser usage are hard to compare sensibly with NetMarketShare's, as they are sliced and diced differently (eg, Safari on iPhone and iPod touch are listed separately, while Safari on iPad appears to be lumped in with 'others').