lol, well, if it makes you feel any better, i recently took a drive down I-81 from I66 to blacksburg, and didn't experience a single drop out on the round trip...
so it works in lands of cows too...
(note, if you do live in a rural area, there are less likely to be XM repeaters, so Sirius might get a better signal, less likely to be blocked by hills/trees etc... I am just guessing, but from what i've heard this seems logical)