Satellite radio service XM on Monday announced that a beta version of its co-branded digital music store with Napster is now available. The software will allow users to listen to more than 70 XM channels, as well as download music they hear on the service.

The interface would also enable a user to mark songs as they hear them on the radio for later download. Customers would also be able to browse the rest of the service's catalog like the stand-alone version of the Napster service.

XM and Napster embarked on an exclusive long-term partnership in July. The deal will bring portable music players to the market with the capability of listening to XM radio and marking songs for download on-the-fly, which would transfer automatically when the device is synced.

Players with this technology from Samsung are expected shortly. The devices would also be able to record XM content when docked.

"XM + Napster brings two best-of-class brands together for the most comprehensive, flexible digital music experience possible," Napster CEO Chris Gorog said in a statement. "We are proud to once again be leading the industry in innovation by merging on-line music with satellite radio."

Subscribers of XM wishing to try out the service can visit the XM + Napster Web site. The software requires Windows 2000 or XP, and utilizes Windows Media 9 DRM. No version for Mac OS X is available.