Mike ditched Napster To Go for the same reasons I did. However, I ditched them a few months ago when they were still in beta and I was beta testing the Creative Portable Media Center. I found lots of problems with Napster's implementation and as such figured they would probably not fix them any time soon. Looks like their 1.0 of Napster To Go doesn't fix them.
Lets hope that MSN Music offers the subscription all you can eat service with a software user experience that does not suck.