Well, the old napster was. Today's napster, i'm not sure of any legal issues. Today it's a legitimate pay service.

You pay a monthly fee
Can stream all the music you want
Can download all the music you want to a MP3 player but, you must tether your mp3 player to your computer so it can sync up with Napster like once a month or the songs stop working.

I really like the service. I use it everyday at work.