How would I determine this? I bought the car used, and it's obvious XM has not been activated. I asked the dealer, he said "No, Grand Prix's didn't have XM until 2008" . . . duh, what? (idiot!) Anyway - I need to determine if it is XM capable, and if it is, how do I activate? Would XM just need the VIN? Sorry for all the questions. Thanks !