Untether your subscription-based music! Microsoft's latest DRM for Windows Media (commonly known as Janus) allows you to transfer tracks from subscription-based services to any compatible MP3 player. In essence, you can "rent" tracks for a monthly fee, then take them with you wherever you go. When your subscription ends, your music won't play anymore. In this type of portable music service, you don't have to purchase each track individually to get them on your device. The technology first appeared in Windows Media Player 10.0 last fall, and hardware manufacturers are quickly catching up. At this point, the only services of this type available are Napster To Go, which features more than a million tracks, and the lesser-known FYE service, while CinemaNow is available as a movie subscription service. Musicmatch On Demand will follow soon. On the hardware side, most major manufacturers, such as Dell, Creative, and Rio, will be offering this feature on their newest MP3 players. Here are a few Janus-compatible devices.