Making the switch from traditional radio to a satellite radio system requires more than just a few choices. The first and most important choice is which of the two satellite radio services to choose, and in the United States it's between XM Radio and Sirius Satellite Radio. These two services have plans to merge by early next year, but for the meantime consumers must choose only one. The satellite radio system, accessories and subscription will all need to be from the same satellite radio provider.

When it comes down to it, the biggest difference between XM and Sirius is the programming choices. Both satellite radio services offer lots of channels, but there are a few different on-air personalities and sports programs that are exclusive to one of the providers. Consumers can easily go online to check the programming on either of the services' Web sites. There are also great opportunities to win free XM or free Sirius on the Internet, which may obviously sway people's preferences in one direction.

Basically, XM has 150 channels and Sirius has 120 channels. With a Sirius satellite radio system, consumers have access to 65 commercial-free music channels and 55 talk, news, sports and entertainment channels. XM, on the other hand, offers 67 music channels, many of which are commercial free. They also offer 30 other channels that stream similar choices to Sirius' talk, news sports and entertainment channels. The number of other available channels on XM is subject to change. Both of the satellite radio services also offer weather and traffic to 20 major U.S. cities.

The big difference is the on-air personalities and sports programming that are offered at either XM or Sirius. Sirius has Howard Stern, for example, and XM has the first 24/7 channel to exclusively offer Major League Baseball. Consumers can easily compare the lineup at their Web sites.

The subscription cost for these satellite radio services is not too different. XM Radio is $12.95 per month, but consumers can get lower rates for longer commitments. Sirius Satellite Radio is $12.95 per month, and they also offer lower rates for longer pans. Consumers also have the options to cancel their XM or Sirius subscriptions at any time when they choose to go month-to-month for the full price. The difference here is that XM offers a pro-rated refund on longer plans and Sirius has a $75 dollar cancellation fee on prepaid subscriptions.

Both satellite radio services offer equipment options including a satellite radio system for permanent installation and a portable satellite radio for listening in the car, home or anywhere else. Each service offers comparable products in similar prices ranges, but they go by different names. Consumers must buy equipment that is compatible with their satellite radio subscription for the meantime, unless things change with the pending merger.

Both XM and Sirius have very functional Web sites where consumers can find out information, see programming schedules, read news, see subscription plans and activate their subscriptions. XM offers looped samples of their streams to Web visitors, so they can hear the listening possibilities. Sirius subscribers can listen to all the streams across the Web once they are issued a log-in password.

Whether it's XM or Sirius, the satellite radio experience is a world apart from traditional radio. Maybe that's because the broadcasts are streamed down to each satellite radio system from a location that actually is out of this world.