Answer: There are no subscription fees for using a satellite navigation system. The system calculates your position using free government GPS satellites, then pre-loaded map software displays your location and directions on the screen. Once you have the unit you can use the pre-loaded software as long as you wish at no additional expense. The map software also includes information about local points of interest such as entertainment, restaurants, banks, ATMs, shopping and emergency services. You can search by name or location type to find destinations, get directions or obtain business phone numbers.

Most manufacturers recommend you update maps at least once per year. It is not absolutely necessary, but high-growth areas can change as much as 20 percent annually. How often you update is up to you and how satisfied you are with the way the unit is performing. A typical update costs $65 to $80 and is usually provided via DVD through a USB connection.

Now available are two groundbreaking GPS systems incorporating cellular modems, the Internet-connected Insignia NS-CNV10 and NS-CNV20 from Best Buy. Both have Google Search to find points of interest and show real-time gas prices for your car's location. For easy destination entry you can use Google Maps on your computer and forward destinations to your unit via e-mail. Both units pair with your Bluetooth phone for hands-free operation, and current local traffic information is provided in the corner of the screen.

The units sell for $399 and $499 (different screen sizes) and include a year's worth of connectivity, as well as quarterly map updates by a technician at any Geek Squad location. After the first year, the annual cost for connectivity and quarterly map updates is $99. The updates alone are a great value since you get four updates installed for little more than the cost of a single map update DVD. I tested the NS-CNV20 and found it to be a very good nav system and especially loved the search, gas price and traffic features, but found the Bluetooth speakerphone volume to be too low even when maxed out. Use your earpiece instead.