I have Windows 7. I downloaded Spotify about a year and a half ago, and it has worked flawlessly ever since. I have a free, unlimited subscription, thanks to a generous Mudcatter. Now that it has opened here in the U.S., I get a few commercials with the free edition and I suppose I'll have some limitations in the future. The commercial-free, unlimited edition is $4.99 a month. Spotify seems to have most of the Smithsonian Folkways, Topic, and Rounder catalogues.
Max has unlimited Rhapsody for the same $4.99 a month, and he swears by it.

-Joe-