Looks a bit sus to me. Read their FAQ and you will see they don't have the music files themselves but give you access to programs that can get them. I would guess that when you sign up they will give you links to programs such as Kazaa, edonkey, emule etc., which you can go to yourself for free. If this is the case I can not see how they claim it is 100% legal.
Virgin allows you to downlaod tracks from 50p click here click here