Music fans are always forced to make a number of tough choices: Beatles or Stones? Vinyl or CD? Live show or studio album?

The advent of legal online music stores has added another factor into the mix: Buy or rent?

Many of you are probably aware of the iTunes Music Store (iTMS). It works like this: You select a song and download it, usually at a price of about 99 cents. After that, the song is yours forever. You can listen to it as many times as you want, put it on an iPod, even burn it to a CD. You've bought the song.

The recently announced Napster To Go, on the other hand, has an entirely different philosophy. You can download unlimited songs from the Napster catalog as part of your $14.95-per-month subscription, but as soon as you stop paying, the music disappears. You've rented the song.

I'm not going to get into the nitty-gritty differences between the two services, for a few reasons. First, new programs and services are appearing often, and the state of the market is far from fixed. Second, there's been a lot of arguing in geek/music communities about the way these services are advertised, such as Napster's questionable "Do the math" spots (which imply that it would take $10,000 to fill an iPod with 10,000 songs, completely ignoring the fact that most people's songs are ripped off CDs they already own).

But the third, and most important, reason that I'm not going to pit the iTMS against Napster is that the core difference in the approach the two take is far more interesting.

As is to be expected, each plan has some benefits and some drawbacks. The main benefit of the iTMS approach is that once you pay for a song, you don't have to continue paying to keep it. Consider the case where you only want to buy one album. You'd pay probably $9.99 for the download, and that would be the end of it. With Napster, though, you'd be paying $180 per year in perpetuity, or at least as long as you want to keep the song.

Of course, with the iTMS approach, you're probably more likely to download a smaller number of songs, since each one costs you more. The marginal cost of each additional song on Napster is zero, so there are no constraints (other than the hard-drive size of your Napster To Go-compatible MP3 player).

Penn State has graciously decided to provide all students with "free" access to Napster's premium service. Though this isn't quite the same as the Napster To Go service, I think it might dissuade a lot of students from experimenting with competing services. It would have been nice to see iTunes certificates or something along those lines offered to students, but the decision has already been made.

So far we've only looked at this issue in terms of online music. Zoom out with me and take a look at this issue from a higher level.

Companies such as Microsoft have made no secret of their desire to sell software as a service. In the future, you might pay Microsoft each month for the pleasure of using Office. Heaven help you if your subscription happens to run out right in the middle of writing a term paper.

In practice, of course, the near-yearly updates to Office which pack features nobody will ever use and cost $330 create a de facto rental program. But that's another issue.

OK, let's get back to ground level.

The iTMS plan is superior. Music is something you're supposed to buy, keep forever and enjoy until the vinyl cracks or the CD scratches.

It always makes me sad to see used albums for sale at music stores. I can't help but wonder why people would want to part with something that can bring so much joy and comfort.

So buy a song, listen to it 300 times and make all your friends listen to it, too. Don't put music on the level of a magazine that is thrown away when you're done with it.