Apple will turn its sights on the vulnerable prey of Microsoft’s Windows Vista today (7 August) when it previews “Leopard”, the next version of Mac OS X.

At its Worldwide Developer Conference in San Francisco, Apple is expected to release details of Leopard, which is due for release late this year or early next – a similar schedule to Vista’s.

Mac OS X sales remain modest compared to Windows but Apple’s share is growing rapidly on the back of Intel-based systems and attractive designs. Microsoft, by contrast, has been uncharacteristically weak with a stuttering release schedule and unconvincing arguments for upgrading, leading to slowing PC sales growth.

Although enterprises are likely to be last to adopt Macintosh systems, the release of software such as Boot Camp and Parallels has made it easier to run Mac OS and Windows on the same systems. Some reports suggest Apple could build Boot Camp into Leopard.

The AppleInsider site has suggested Leopard’s feature set could include voice over IP (VoIP) and mapping software.