The Justice Department gave Sirius and XM the green light to merge. Other than higher monthly prices (probably), the impact will be minor. With only one satellite radio standard in the future, odds are that more cars will come with a satellite tuner built in to the radio, making it easier and cheaper to add satellite radio service at any during the life of your vehicle. On higher-end cars, the antenna will probably come installed, too, and you'll get 90 or 180 days free service as a teaser.

Who's unhappy and carping? The terrestrial radio competitors (regular radio stations) who realize satellite gives you more music choices with fewer commercials (for a fee) and the HD Radio competitors who've been struggling to make headway in the car market. They're going on and on about the unfairness of the Justice Department giving the merger the go-ahead, just because Sirius and XM declared, a decade ago, that they'd never, never, ever merge. Hey, a minor technicality.

Here's what's going to happen within five years--10 reasons why it's not such a big deal for most people:

* Both services may or may not continue broadcasting. If you guessed (bought) wrong and, say, the Sirius satellites stay on the air but not the XM satellites, well, that's life, and you're out $100 for the add-on tuner you bought. Nothing lasts forever. Both will continue broadcasting so long as they get more revenue than it costs to keep the dual satellite systems active. Cheer up: You could have bought an HD-DVD player instead of Blu-ray.

* Satellite radio prices will go up. (Like you need to be a genius to figure this one out.) The two kept each other's prices more or less in check. Broadcast radio isn't a complete competitor, nor is HD Radio.

* HD Radio's premium will come down to zero. Right now you can pay as much as $350 extra for HD Radio in high-end cars. (In replacement radios, it's hard to see much if any price premium.) It's a nice feature for getting additional programming when you're driving around town but it dies as you drive to the countryside, and the signal falls off faster than analog radio does. The Justice Department appeared to agree that HD Radio is a satellite competitor. It is, for about 20 minutes after the tallest building downtown fades from your rear view mirror.

* With only one satellite standard in the future, odds are more automakers will just bundle in the one-and-only satellite tuner chipset and hope the take rate increases enough to cover their added cost of goods.

* You'll get about the same music you got before - decades, classic rock, talk radio, hip-hop, Spanish language - because most of the programing is interchangeable.

* In the future you'll likely be able to get the exclusive programming you really wanted, such as Howard Stern, Opie & Anthony, leftist commentary, NASCAR, and the bass-fishing channel, on the service that doesn't currently carry it, for a couple dollars a month extra. That's probably progress.

* Additional services will make satellite radio interesting to some fence-sitters: those who want real-time traffic information and graphical weather reports (not just a repeating audio channel).

* There'll be more satellite video programming, mostly kid stuff for the backseat, where the audience is less critical if you drop 5 seconds of programming going under a bridge.

* Cars will be fractionally safer. Any built-in audio device that you control with the existing radio head unit is safer than a stick-on modules with tiny buttons and hard-to-read displays.

* The real competitor to satellite radio near term is the iPod--music is music--and longer term, it's streaming cellular, Wi-Fi, and WiMax to the car. As the cellular network expands, there will be fewer places you can't get a cellular signal that could be streaming music.

One versus two satellite radio networks will make or break some investor fortunes, but it really doesn't change most of our lives. I love satellite radio in cars. When I don't have it in a test car, I plug in an iPod and life is just about as good.

Let's make sure the Justice Department is spending enough time (or spending less time, if you don't trust them as far as you can toss them) investigating whether electronic voting machines are really tamper-proof or if Wall Street bandits-in-neckties cut corners that helped fuel the current recession. The job of the Justice Department is to make sure the bad guys face the music.