i know a lot of people out there are fans of music and downloading music.
one of the most successful "legit" music downloading service was iTunes for Mac. today iTunes for Windows finally came out.
you can check it out at apple.com/itunes. it is Free to download and use.
also - its more than just a music store, its a media player, kinda like Windows Media Player or Winamp. it has built in streaming music (you dont have to pay for it, its free), visualizations, and some other stuff.
it also has the slick MacOS X interface, which a lot of people like.