I also never use Napster. It shouldn't be necessary, even for audio. As long as you can play it in Windows Media Player, you should be able to remove the DRM. The wma/v file should have a URL inside it that tells it where to go to get the licence file (used in conjunction with your IndivBox.key for generating the content decryption key) and the only way I can see that needing napster is if you downloaded the music with napster and they use their own web server for it (which requires authentication) - in which case, you would already have napster.