I've had XM Radio since October of 2001. Get XM as soon as possible. You will wonder how you lived without it.
Get the MyFi. This is like having an IPOD but you don't have to dick around with downloading songs, etc. The unit can save 5 hours+ of content for later playback. Or you can even set it to record something new everyday.
This unit comes with the accessories to connect it in your car, in your home or put it in your pocket and take a walk.
Awesome unit.