icrosoft's operating system runs on 90.85 percent of the computers identified by NetMarketShare, well ahead of the 7.54 percent for Mac OS and 1.61 percent for Linux.

Broken down further, Windows 7 is the most popular (60.98 percent), well ahead of the newer version of the system, Windows 8.1 (13.2 percent) and, even more surprising, Windows XP (11.98 percent). In comparison, the most recent version of Mac OS X, Yosemite, is only running on 4.54 percent of the computers surveyed.

With the launch of the latest version of its operating system, the trick will be for Microsoft to maintain its advantage over the competition by both attracting new clients and, even more crucially, by convincing Windows 7 faithful to upgrade to 10. To help accomplish this, Microsoft has already announced that for the first year, upgrades from Windows 7 and 8.1 to 10 will be free.

Windows 10 for PC and tablets will come out on July 29 in 190 countries.

It will include several new features, such as a new "Start" menu, integration of the Cortana intelligent assistant, a new look Windows Store, new "Maps," "Photos" and "Xbox" apps, the Microsoft Edge web browser, a "Continuum" mode and even the now famous "Candy Crush" game.