The two companies took different tacks to distribute the first versions of their next desktop operating systems: the Windows 8 preview free of charge, while Apple limited Mountain Lion to registered Apple developers, people who had paid a $99 annual fee to receive early Apple code.

While Microsoft boasted last year that of Windows 8 Developer Preview had been download between Sept. 13 and Dec. 7, 2011, Apple has not divulged the number of developers who downloaded Mountain Lion's preview.

The percentage of users running a preview may be in Apple's favor, but Microsoft has the clear advantage in sheer numbers, since Apple's global usage share is only 7% to 8% of all personal computers, while Windows' is between 90% and 92%.

According to Chitika, more Mac users are still running Mac OS X 10.6, aka Snow Leopard, which accounted for 47.5% of all Macs. OS X 10.7, or Lion, garnered a 30.5% share.

Those numbers were similar to the ones published by Internet metrics company Net Applications earlier this month. Net Applications had Snow Leopard accounting for 43.4% of the Mac OS X market during February, with Lion at 38.9%.