Moshe Bar, a technology entrepreneur, said he has been able to run both FreeBSD Unix and Debian Linux on a new Mactel machine using virtualization software from XenSource Inc., which he co-founded. But Apple's protectiveness of its hardware specs has so far prevented Bar from getting the graphics, sound or Wi-Fi to work.

"I'm a text command-line kind of guy, so it's OK," he said. "Given enough time, someone should be able to make the drivers work."

Bar said that Windows won't be able to run on MacIntels on top of Xen until the summer or fall. By that time, most PC vendors, including Apple, will have begun shipping desktop computers with processors that have Intel's Virtualization Technology built-in.

Getting Mac OS X to run on top of Xen, is ironically the most difficult task, Bar says, because OS X has its own virtualization technology that interferes with Xen's. The work-around, Bar says, is for users to simply set up their MacIntel for dual-boot: Mac OS X or Xen, with the latter supporting Linux, Unix and eventually, Windows on top.

Bar said he plans to release a how-to guide on the Internet.