iTunes for Windows available at
www.apple.com - nice toy to try out some Apple software.
It installs quickly and can use your existing music files.
The Music Store is slick, you can very quickly sample music from CDs and if in the USA buy it. a track at a time.
They have some tunes in Dance and Electronic but not a lot.
A similar Canadian music store opened this week,
puretracks - I think they use .WMA file format which probably has some kind of digital rights management in it, like the Apple AAC format.