“One in four Macs now run OS X Mountain Lion, Apple’s newest operating system, data released last week showed,” Gregg Keizer reports for Computerworld. “But there are signs that OS X Snow Leopard, an edition shipped in August 2009, may be the Mac’s equivalent of Microsoft’s Windows XP, an OS that stubbornly refuses to go away.”

“Mountain Lion, also known as OS X 10.8, accounted for 25.8% of all Mac operating systems during October, according to statistics from metrics company Net Applications. That represented a three-and-a-half-point increase over September,” Keizer reports. “Apple issued Mountain Lion on July 25… While Apple customers running Snow Leopard can upgrade to Mountain Lion — assuming their Macs meet the requirements — they have done so in far fewer numbers than those who relied on Lion. Since Mountain Lion’s debut, Snow Leopard has lost 6.6 percentage points, a drop of 17%. Meanwhile, Lion has lost more than double that — 15.6 percentage points — falling 33% since July.”

Keizer reports, “Snow Leopard is no Windows XP — for one thing it’s less than one-third as old as that 11-year-old OS from Microsoft — but the comparisons, what with both posting slow-but-steady declines and their makers’ extending security support, are intriguing. It’s unclear why Mac users are holding on to Snow Leopard, but one factor may be that it is the newest Apple OS able to run applications written for the PowerPC processor, the Apple/IBM/Motorola-designed CPU used by Macs before Apple announced a switch to Intel in 2005.”

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