In a move that at least one analyst says will make it more confusing for people with non-Apple portable media players, Microsoft on Wednesday replaced its "PlaysForSure" logo with a "Certified for Windows Vista" tag.

The certification is used to guarantee compatibility with Microsoft's copyright-protection software and is the same logo used for the company's Zune player. The problem, however, is that music and video bought from the online Zune Marketplace won't play in their native format on other devices, including those that will carry the new logo.

"Very confusing," Michael Gartenberg, analyst for JupiterResearch said of the change. "This thing goes beyond name changes. It once again looks like they've dropped the ball here."

Microsoft was not immediately available for comment.

The logos reflect the digital rights management technology Microsoft uses to control how and where downloaded content is used. PlaysForSure was used to match online stores with players from multiple vendors supporting Microsoft's digital rights management (DRM) technology.

That part of Microsoft's business, which really revolves around licensing, is separate from the company's Zune business. The specific licensing is Microsoft's attempt to beat market leader Apple using a similar combination strategy of branding and DRM technology. Both companies have built online stores that sell music and video tied through DRM technology to their players, which means the content is not compatible in its native form with other products. Such a closed-system makes it less likely customers will switch as they buy more products.

DRM has been an uphill battle for Microsoft, in that the company has tried to provide a system it can license for use across devices from multiple vendors, while at the same time developing its own DRM system for the Zune. The company's latest choice is a reflection of this duality within Microsoft, Gartenberg said.

"The licensing arm is only interested in spreading adoption of Microsoft technology; hence the decision to link music downloads to Windows Vista, which will eventually replace XP in the market. The Zune unit, on the other hand, wants to keep its technology closed. "It goes to show how Microsoft is not always in lockstep with itself," Gartenberg said.

Companies building players that supported PlaysForSure DRM included SanDisk, Sony, and Creative Technology. Even among those devices, however, content bought from online stores didn't always work. "(PlaysForSure) was a good idea that was poorly executed, which is why we started calling it 'PlaysForAlmostSure," Gartenberg said.

Ease of use is also an important element in the sale of portable media players. A key element to Apple's success is in its ability to make buying, organizing and downloading content from its iTunes software to the iPod easy.

The market for portable music and video players has become a multi-billion-dollar arena. Revenues this year are expected to reach $19.5 billion worldwide, with vendors forecast to ship 211.5 million units, according to iSuppli.