The Microsoft Store is the location for finding and buying new Windows 8 apps--the ones that you load off the Start screen. You need a Microsoft account to buy apps, or to download the many available free apps. Note that desktop software may also be listed in the store, but clicking on those tiles will just take you to the manufacturer's website. You can't download desktop software from the Windows Store.

The Music app is confusing, partly because it's labeled "Xbox Music" once you click inside, and because it's a location for both purchasing music (as with iTunes or Google Play), as well for listening to free streaming music (as with Spotify or Rdio). You can also play your own music, but the interface for local file playback is obtuse to say the least. Luckily, Windows Media Player is still available on the desktop for when you need a more robust music playback app. If you're an iTunes user, you can just download and install iTunes. iTunes works fine, but it's currently a desktop-only app.