That's the question our new friend Frank Giovinazzi asks over on AIADA's site. He breaks down the line-up of Sirius versus XM pretty well. Stern's move to Sirius in a few years might get a few thousand new subscribers over to Sirius' side but its alliances with big manufacturers that are key. Right now Sirius is making all the right moves, although I like the integration of XM satellite in GM vehicles a bit better than what Sirius has done so far. The key is that after new car buyers get the option they're usually hooked. I love being able to surf such great clarity stations with no commercials. Plus BBC, CNN, ESPN, and yes now Howard Stern, junkies can get their fix too.