Michael Robertson's last startup, MP3.com, helped ignite the digital music revolution, attracting a big buzz and lawsuits from major record labels.

Robertson's latest gig is no less ambitious: an operating system called Lindows that aims to run programs designed for Microsoft Corp.'s Windows.

The gist: No Microsoft purchase necessary. Lindows is being built to run on the Linux operating system.

Lindows.com Inc. is attracting considerable attention — and skepticism — just months after it was announced. It is also fighting its first lawsuit, from Microsoft, for alleged trademark infringement.

"Anytime you're trying to change the world, you're going to encounter challenges," said Robertson, who sold MP3.com last year to Vivendi Universal SA but still serves as an adviser.

If delivered as promised, Lindows could do nothing less than crack Microsoft's monopoly on business and home operating systems — in effect succeed where antitrust regulators have so far failed.

If Lindows works, it would provide an alternative that's easy to use and runs efficiently but costs about half the full retail price of the home edition of Windows XP and plays well with real Windows-based systems.

And if it wins customers, it could open up a vast library of Linux software and opportunities for programmers in the open-source community.

But those are big 'ifs.'

Lindows has offered few details about its product. On Jan. 24, it offered a $99 download of a "Sneak Preview" on condition the information not be made public.

Public releases are expected later this year.

Even if Lindows works, analysts question whether it will find traction among consumers who have largely rejected attempts to make Linux palatable for the masses.

Linux, after all, has not made headway into desktop PCs despite low costs, user-friendly desktop environments and programs that claim to be compatible with Windows, including Sun Microsystems Inc.'s Star Office.

It may simply be too difficult.

"Look at Star Office. Here's something that's already interoperable with the world-accepted standard of Microsoft products," said Matthew Berk of Jupiter Media Metrix. "Why hasn't it found wider adoption?"

Sun tried in the mid-1990s to create software that could run Windows programs in its Unix-based Solaris operating system. The so-called Wabi project was shut down in 1997.

"They didn't put enough money behind it," said Rob Enderle, an analyst at Giga Information Group. "It was a special project and for the most part it was never funded to a level that would have allowed it to succeed."

Since 1993, a loose community of Linux and other Unix programmers in the so-called Wine project have been working on free software that allows Windows-based programs to run in Linux.

Despite all that effort, Wine remains difficult to use and is far from 100 percent compatible.

Lindows will use components of Wine but also is improving them, Robertson said.

The new operating system promises much greater simplicity than any other Linux distribution and file navigation that is familiar to Windows users.

Lindows also will have a more liberal licensing policy.

With one license, users can legally copy Lindows to a home PC, laptop and work computer. Microsoft would charge for each.

Lindows isn't promising the world. At first, its focus will be on office productivity applications such as Microsoft's Office Suite and Lotus Notes.

Rather than reverse engineering software, Lindows programmers look for how the program interacts with the operating system and then replicate that in the Linux environment.

"It's much like French and English. We say cheese. They say fromage," Robertson said.

Lindows is attempting to accomplish its goals without any help from Microsoft. Analysts wonder whether that may be too big a task for its two-dozen employees and limited funding.

"It's not just a matter of watching how it works," Berk said. "I think you need to have a relationship there."

Microsoft, for instance, could make changes to its operating system or its programs that render Lindows obsolete.

But Robertson might have an ally in the suggested remedies proposed by state attorneys general who are not adhering to the proposed antitrust settlement between Microsoft and the federal government.

The dissenting states want Microsoft to be forced to share more of the inner workings of Windows and other programs.

So far, Microsoft isn't saying much about Lindows beyond its trademark infringement lawsuit, which was filed in December.

"If Lindows were to cease using the name Lindows, then we would have no problem at all with the product itself," said Microsoft spokesman Jon Murchinson.

The Microsoft suit intends to try to slow down Lindows development and scare away investors, said Robertson.

"We're not on a jihad here against Microsoft," he said. "We're on a mission to bring choice."