Don't call it a comeback because Michael Robertson has been in the music space for years. Today, though, Robertson will unveil a new music service along with companion Linux hardware and software applications that create an alternative to Microsoft and Apple's digital entertainment hubs.

At 6:30 AM PST, Robertson, CEO of the desktop Linux firm Linspire, will unveil MP3Tunes.com, his first digital music product in four years. His last foray, MP3.com, had an Icarus-like trajectory, once enjoying a $65 per share stock price before being felled by hundreds of millions of dollars in lawsuit payouts and swallowed by Vivendi Universal, one of the conglomerates that originally filed copyright infringement lawsuits against the company.

The new service stays true to Robertson's tactics, both old and new: The song catalog highlights unsigned and independent artists, features no digital rights management, and runs on Linux. While MP3Tunes plays it safe and will only offer non-major label music, it's more than just a download service.

Visitors to the Web-based MP3Tunes.com can purchase individual MP3 songs (encoded in a high-quality 192-kbps rate) for 88 cents or a single album for $8.88. Currently, the service is launching with music only from the distributor CD Baby, which specializes in unsigned artists, or artists whose labels allow them to offer DRM-less songs for sale online. CD Baby has 415,000 songs that will be available on MP3Tunes.

Once a user signs in and downloads a song, a copy of that song stays inside each purchaser's "online locker" at My.MP3Tunes.com, and is available for re-download at any time, free of charge, when you return to the service.

"It's like a junior version of My.MP3.com," says Robertson, comparing it to the music locker service at MP3.com that eventually led to his downfall. "Once you download this music and you prove that you bought it, you can access it forever."

It's a simple concept, yet one that in today's DRM-based online music world is pretty compelling and highlights a jarring fact: Whether you're purchasing music from Apple's iTunes or Napster's new ToGo program, users never truly own your music outright.

Apple, for example, dictates the number of computers on which a song can be played. With Napster, the restriction is more upfront and the basis of the business model: You're renting the music. Cancel your subscription and the music disappears. 

Following in Apple's footsteps, Robertson is hoping that his move back into the music space will help jumpstart sales of his Linux products. To that end, he will also unveil a digital music hub program called MP3beamer, which will be sold for $20 as a standalone piece of software for Linspire users. A combination package of the Linspire operating system and the MP3beamer program is also available for $79, or as part of a Linspire-based "music appliance" desktop for $400.