XM vs. Sirius

I am definitely interested in getting the better of these 2 formats for my car. Which is better and how much should the tuner cost professionally installed?
One company isn't better than the other in all situations, so what is better depends on more personal specifics than you have shared. I like XM only because I like Alpine and hate Sirius' associated "ready" head units. What it costs depends on the tuner model and the store installing it. Make some phone calls and don't cheap out on the installation.
I went with XM instead of Sirius because of hardware not software. I went with the seperate unit and not a complete head unit as the Pioneers take up very little space. Both XM and Sirius are equal in sound qaulity and there formats are very close but I still prefer XM. Can't go wrong with either and you can save $$ if you do the install yourself as they take only a few hours to do. Happy Listening!
Please be more specific re:cost and what car unit to buy. I am not a DIY guy so installing it myself is not an option. Thanks for the info. Also I lease my car so it must be restored to normal radio when I turn it back in.
In my wifes car, we installed the tiny Alpine unit with a remote C/MP3 changer. Works great. My other car (Acura) came with XM. I like XM.
Jsonic, Goodguys, Circuit City and Best Buy are all places that can help you out first hand. I paid about $100 each for my pioneers and at the time they were having a $50 installation but choose to install them myself as they were easy to do. Iv'e leased cars that I put after market equipment in and never had any problems when I turned car back in, the only thing is I was out the equipment but I didn't care as this was a chance to upgrade!
That's very helpful. The guy I called in my area wanted 400$ installed. Yeah right!