Gayle,
Do you have broadband internet ? (cable or dsl)
If so you don't need the home unit for Sirius. Sirius allows you to log on and listen to music online for free through your computer. You can still do other things on the computer.
I have Sirius in both vehicles and love it, its the best thing to happen to radio. This April I drove from Vermont to DC and never had to change stations or lost signal even in the mountains, no commercials either.
I bought the cheapest XAct unit for both vehicles, installation was a snap. The unit could move into the house if I bought the home base unit but since I can listen through my computer why spend the extra dough?
A couple of the car manufacturers are working with Sirius on the next generation to include 6 channels of kids tv to keep the kiddies busy in the car!
Dave