I've had XM radio both at home and in my car for a couple of years. I recently bought a 2007 Nissan that came equipped with Sirius radio. I was told that it was XM, but when I picked the car up I found out it was Sirius radio. I went ahead and signed up for Sirius not knowing that the programs are completely different. My question is this: Can an XM receiver be switched into the in-dash radio? I know I can put my XM external receiver in the car, but I would like to avoid this.