Napster's big switch from selling Windows Media files wrapped in Microsoft's copyright protection to selling unprotected MP3s is good news for those of us who have been waiting upward of 10 years for a digital music market in which companies that don't happen to sell the top MP3 player in the world can compete.

However, the big losers whenever a music store abandons DRM are existing customers of the store. They tend to find themselves with lots of unplayable music files -- just ask a former customer of Sony Connect or MSN Music (assuming you can find one).

The issue shows what is wrong with DRM so clearly that even your dad could understand it. If companies on the scale of Sony and Microsoft failed to figure out a good way to let people keep listening to purchased music after their DRM-ed music stores shut down, what hope is there for smaller firms such as Napster -- especially because it used an outside DRM provider (Microsoft) to protect its files?

We decided to find out, after a reader left a comment on our post about Napster's MP3 announcement: "Does anyone know if WMA DRM songs previously purchased from Napster can be redownloaded as DRM-free MP3s?" the reader asked. "I'd like to know before reinstalling [the] Napster software, which I gave up on once Amazon MP3s came online."

We put the reader's question to Napster. Here's what the company had to say.

Napster spokesman: Currently there is no program for re-downloading or upgrading. The tracks have to be purchased in [the] MP3 format.

Wired.com Listening Post: Will DRM-ed tracks purchased earlier from Napster continue to play (and if so, for how long)? Will the licensing mechanism that renews tracks when you upgrade to a new computer still work?

Napster spokesman: Yes. There will be no problems with Napster DRM-ed tracks.

So, there you have it -- some good news (Napster and Microsoft will apparently continue to support Napster DRM on old tracks), and some bad news (Napster won't give you unprotected versions of the music you've already bought, and it's still unclear how long Napster/Microsoft will continue to support PlaysForSure-protected files as users upgrade to new computers).

In Napster's defense, there are plenty of other ways for its customers to replace their DRM-ed purchases with MP3 copies of the same music.