I used the method described earlier in the forum using to Winamp and the out_stacker plug, and I combined it with an out_MP3 plugin that you can also get from the winamp site. With the Radium MP3 codec, this works wonderfully. I've been listening to both versions at high volume to try and see if I can hear a difference and I can't.

Yes, this is real time encoding so it's not ideal, but it works. You could leave an album playing and watch TV or do it in the background - it ain't that bad!

You could use this method on the protected files you download from Napster for free, although it would be illegal...