So in theory, XM wants you to buy:
$12.95 - "Traditional" Satellite Service for Your Car/Handheld Satellite Receiver
$7.99 - "XM Radio Online" for the privilege to listen to the SAME channels you are already paying monthly for above, while at your computer
$8.99 - "XM Mobile" for the privilege to listen to the SAME channels you are already paying
TWICE monthly for above, while not at your computer, in your car, or with your handheld satellite receiver (which would be
where, exactly?)