Do You Have Satellite Radio?

This year I have two basic purchases that I intend to make. I need to get a GPS for my car and I also want to pick up a satellite radio system.

So I am interested in finding out how many of you have a satellite radio system in your car and your opinions about it. Do you have a preference between XM and Sirius? What equipment do you recommend?

Any advice is appreciated. Thank you for your help.