OS X Market Share: 8.23 Percent Down, 82.06 Percent to Go …

Historically, Apple’s September back-to-school promotion has been a great driver of sales and this year was no exception. According to research outfit Net Applications, Apple’s share of the operating system market rose nearly four-tenths of a percentage point in September, its biggest one-month gain since May (click on the chart below for a larger version).

Today, Mac OS X runs on 8.23 percent of the machines accessing the 40,000 sites monitored by Net Applications. Two years ago it was running on a little over 5 percent. That’s a 58 percent gain. Quite an achievement, though at 8.23 percent, Apple’s (AAPL) share of the OS market is still dwarfed by the 90.29 percent held by Microsoft and its Windows OS. That said Windows’s market share does appear to be slipping. It dropped 0.4 percent from August to September.