Microsoft’s has taken a bruising in the Japanese marketplace just as Apple’s Mac OS X Leopard was released, according to a new report by the country’s Business Computer News. The publication notes that while sales of Mac OS X increased dramatically between September and October, climbing from a rate of 15.5 percent year-over-year to 60.5 percent, Microsoft suffered from the reverse effect. Sales growth of Windows plummeted from 75.3 percent to 28.7 percent. The sudden switch provided Apple with about 53.9 of the total OS-only marketshare in Japan during October — a breakthrough for the company, BCN says.

Although the results are expected to cool in the wake of Leopard’s release, the reversal highlights several factors that provide Mac users a stronger incentive to upgrade outside of their normal computer replacement schedule than for Windows users, the report says. Microsoft is charging more for Vista in Japan, offering the upgrade-only Vista Home Premium package for 19,600 Yen ($179) and 30,300 Yen (£176) for a full version; Apple’s full standard OS sells for 14,700 Yen (£94). Pricing for the Mac version is also less intimidating and includes just a single version compared to the several full and upgrade copies of Vista buyers encounter in the store when updating their systems. Less stringent minimum requirements for Leopard compared to Vista upon their respective launches are also said to improve the appeal of the Mac OS.