Hi Mayo,
I can't compare satellite to cable radio, but I will put in a plug for XM. We've had XM in two trucks now for over a year. We love it.
There is a huge variety and not just music, but talk, news, sports, books, comedy..lots.
If you're contemplating a system, I would recommend one of those that moves back and forth between car and house unless you can afford stand-alone systems for each. The only frustration we have with XM is that if you're listening to something interesting just as you drive up to the house, you have to sit in the truck until it's through unless you don't care to hear the end..
And yes, you will need external antennas. The signal is affected by solid cover. A roof/garage/carport/highway underpass/mountain range will prevent you from getting a signal. I've not seen it affected to a great extent by weather, but it is possible that a really thick cloud cover will block you. We have very heavy tree cover in our driveway and if you hit just the wrong spot to stop, the signal will go away. Car system come in separate components with the antenna being just one part. The home systems usually come all-inclusive.
To peek your interest, visit your nearest Wal-Mart. They have some great deals on receivers. Also, check out
http://www.xmsr.com for deals.
I can't speak for Sirius, but their ace is the _NO_ commercials promise. We find that the stations on XM that do commercials are fine..fewer than regular radio, and there are plenty of commercial free stations too. We started with XM because it was out first. We own stock in both so get which ever you like..
