What was far less of a surprise than Vista's fall-off was Net Applications' finding that Windows XP's share dropped again in September: The OS has lost share for 23 consecutive months. Last month, Windows XP fell 0.3 percentage points, a much less drastic decline than in August, when it plummeted nearly four times as far to set a record decline. XP's loss was also about half the monthly average over the last two years.
No one need cry for Microsoft, however: Net Applications puts Windows' total share at a whopping 92.8 percent, an insurmountable lead over its closest rival, Apple's Mac OS X.
Mac OS X climbed nearly the same amount that Windows fell -- 0.25 percentage points -- to finish above 5 percent for the first time under Net Applications revised its methodology. Starting with July's data, the Web measurement company changed how it tallies usage share, and for the first time weighted data by the estimated size of each country's Internet population. That nearly halved Mac OS X's share, as well as reducing Vista's, but pumped up XP's considerably.
Net Applications measures OS usage by tracking the machines that surf to the 40,000 sites it monitors for clients, which results in a data pool of about 160 million unique visitors per month. September's operating data can be found on Net Applications' site.