Microsoft plans to announce Windows Media Player 10 Mobile for Windows-based cell phones and PDAs later today.

The software turns these devices into portable media players that will work with Media Center PCs, allowing users to take content with them. Further details about Microsoft's Windows XP Media Center 2005 and news that Microsoft is to launch MSN Music Store in the US and eight european countries are also to be announced today.

Windows Media Player 10 Mobile also includes support for Microsoft's new "Janus" DRM technology, which allows subscribers to online music services that support the technology to download vast music collections.

The software will ship on many devices, starting with a new smart phone from Audiovox and a new Axim X50 PDA from Dell. Existing devices can be upgraded, but users will have to get an upgrade from the device maker, according to Microsoft.

Also for portable devices, Microsoft is introducing a new logo program called "Plays for Sure". The logo will appear on media players and online music and video services to indicate interoperability.

"When consumers see a device that has the Plays for Sure logo or a music or video service that has the logo, you can guarantee interoperability between those devices and services", Microsoft said.