Apple is conceding that its decision to include a utility in its new Leopard operating system that lets users boot Microsoft Windows could cause some developers to discontinue writing applications for the Mac OS.

In a report to investors released last week, Apple warned that the utility, known as Boot Camp, "may deter developers from creating software applications for Mac OS X if such applications are already available for the Windows platform."

Leopard is officially known as Mac OS X 10.5.

Boot Camp lets users run 32-bit versions of Windows Vista and Windows XP on Intel-based Macs, allowing them to operate Windows applications and games. But Apple fears that some developers will count on Boot Camp to give them access to the Mac market and won't rewrite their Windows apps for the Mac OS.

Only about half of the Macs currently in the market use the Intel processors required by Boot Camp. The rest run on PowerPC chips that are not Boot Camp-compatible. That could leave a large number of Mac users out in the cold if developers start to abandon Mac-only versions of their apps.

Mac sales could suffer if that happens, Apple warns in its annual report. "The company believes decisions by customers to purchase the company's hardware products are often based on the availability of third-party application software," Apple said.

The report was filed Thursday with the Securities and Exchange Commission.

On the other hand, the presence of Boot Camp gives users of Intel-based Macs immediate access to the full range of Windows applications -- which greatly outnumber those available for the Mac OS. That could help spur Mac sales, as many potential Apple customers have until now stuck with Windows-based PCs because of the greater selection of applications.