We posted an article about XM the other day, and it got me thinking about upgrading my car stereo. XM radio seems to be great for folks always on the go. The AM/FM dial usually does fine by me, but the slickness of satellite content is quite a draw. If subscription services work for other forms of audio-based media, then why not give XM Satellite Radio or Sirius a spin? There probably aren't too many paid listeners out there, but I'm sure those numbers will change when more talent move to the satellite bands. Which one will lead, XM? Which one is better, Sirius? I just don't know yet.