I downloaded iTunes for Windows today from Apple. Wow, a very nice application. The music store browser is quick and easy to use. If you find something that interests you, double-click on it and you will get a 30 second sample. The application is a free download and you don't need to provide a credit card to browse and preview songs. I've spent most of the night browsing, sampling, and looking at celebrity playlists. Despite having nearly 400K songs in the library, it's very apparent there are huge gaps. It's a good start though.
