When they envision the future of online music, music industry types still talk about "the celestial jukebox," dreaming of the day when music fans everywhere can access any song they want whenever they want it. That future is going to get a lot closer this year as some new music services begin to offer customers the ability to download as many tracks as they want to their MP3 players for a monthly fee.

Sounds like a cool idea, right? I mean, I know bunch of people who pay $10 a month for a Rhapsody subscription so they can listen to whatever streamed tunes they want to on their PC. Would they pay another $5 a month to get those same songs on their portable player? You bet they would.

This month, I got a chance to try out one of the first of these portable subscription offerings, an add-on to Napster 2's subscription service called Napster2Go. It's a little rough around the edges, but then Napster's classifying the service as a preview offering. The company's planned a real push for portable subscriptions around the expected launch of Napster 3 early this year. But even in this beta-like state, it's clear that portable subscriptions are going to be a great way to find and try new music.

Media Player Plug-ins

You won't find Napster2Go on Napster's Web page or even in the Napster music manager app that you download to access their store. Instead, you download a plug-in that lets you access the service through Windows Media Player 10. Once you've got the plug-in, the service looks almost exactly like Napster 2.0. You can browse through the service's library and pick out albums and tracks to download. Those files go into a queue to be transferred to your PC.

As with the standard Napster subscription, there's no limit on the number of 128-kbps WMA files you can download. The difference here is that, once the files are on your PC, you can transfer any of them to a portable player. Using Windows Media DRM 10, Napster can set the license for each track you download to expire on the day when your subscription to the Napster service expires. Then, the portable player uses a secure clock to check the date on that license and make sure you're still allowed to play the track.

Most of Napster's million-plus-track library is available for download, and in my tests I encountered only a few albums that I couldn't grab, presumably because of licensing issues.

Downloaded albums end up in the Media Player library along with any other audio files on your PC. Transferring them to your portable player is as simple as choosing which songs to sync and clicking a button.

I tested the service with IRiver's H320 MP3 player, which was one of the first to support all the necessary bits of Windows Media DRM 10 to enable portable subscriptions. Several current players, and most new ones that will play WMA files, should be able to work with this type of service. Microsoft's created a logo program called PlaysForSure that lists compatible players.

Growing Pains

Despite the promise of portable subscriptions, my quick trial didn't always run smoothly. As long as I kept regularly adding files to my player and plugging back into my PC, everything was fine. Sure, I'd have preferred higher bit-rate tracks, but the 128-kbps files were fine for trying out new music.

However, trouble started when I stopped syncing my player regularly. I wanted to see what happens when the license for a track expires, so I built up a nice library and took the IRiver player on the road for a month with nothing but its recharger.

The good news: The service actually works. Once the licenses on the tracks expired, I couldn't play them. The bad news: Instead of a nice user-friendly message informing me that I needed to sync my player and update the license, I got, well, nothing. All the player did was pause for a few seconds and skip to the next track. Even worse, while the player was checking licensing details, it acted as if it wasn't responding at all, queuing up all the buttons I'd pressed before I figured out what was going on. That type of behavior has to be fixed before portable subscription services can take off.

Still, apart from that little snafu, Napster2Go worked great with the IRiver player. If future services boost the quality of the downloads--192-kbps WMA files would work nicely--portable music subscriptions could become the hot new way to get music. As it is, Napster2Go looks like a great way to find new music and fill out your digital music library. For $15 per month, you can try out all the songs you'd like to and carry them with you away from your PC, but if you're like me, you'll probably still end up buying your favorites on CD.

Quick Hits

P-to-P Users Beware: In case you needed another reason to practice good PC security, we've come across some strange files being distributed on peer-to-peer networks. These WMA and WMV files look like normal audio or video files at first, but launch a string of pop-up ads and sometimes adware installers when you attempt to play them. Read our exclusive look at what's behind it in "Risk Your PC's Health for a Song?"

In Heavy Rotation

Sunshine for a Rainy Week: As I'm writing this, I can report that it's rained nearly every day here in San Francisco since I got back from my Christmas vacation. Thankfully, one of my Christmas presents was Apollo Sunshine's Katonah, a beautifully scattered pop album that recalls bits of The Flaming Lips, Ben Folds Five, and The Beatles.

Eric Dahl feels bad about disconnecting coworkers from his ITunes library, but he has to shut his PC down sometimes. To comment or ask a question, send him an e-mail.