In July the number of Windows 7 operating system users surpassed Vista users, according to calculations by a leading market research firm. But Windows 7 has a long way to go to overtake the aging Windows XP, which still has more than double the market share of Windows 7 and Vista combined despite being almost nine years old.

Windows 7 had a 14.5 percent share of worldwide usage of desktop operating systems, just squeaking by Vista’s 14.3 percent, according to researcher Net Applications. Windows 7 began selling in October, less than nine months ago, as a replacement for Vista, which was widely criticized for its performance and problems working with third-party devices.

Vista’s market share peaked at 18.8 percent at the time Windows 7 began shipping, according to Net Applications, which based its report on the 160 million visitors to the 40,000 Web sites it monitors.

Windows XP still held a 61.9 percent market share in July. While the number of users of that desktop operating system have been on a long, slow decline – it had more than 70 percent of the market one year ago and has lost 5.9 points of share since the first of the year – it will be some time before the Windows XP and Windows 7 market share lines cross.

Full story: CRN