I'm also focusing exclusively on after-market, automotive GPS receivers-not the kind you take hiking, but the kind you see mounted on people's dashboards. To get started, let's talk about GPS systems in general first, so you understand what they do, what their basic features are, and what additional features you can upgrade to.

What GPS Systems Do

GPS systems (or receivers) are electronic devices that show you where you are on an electronic map and tell you how to get where you want to go via some sort of voice instructions.

All GPS receivers also have a database of Points of Interest (POIs). These are pre-programmed locations of gas stations, restaurants, state parks, hospitals, well-known buildings, etc. Basically these are public destinations.

GPS receivers also all come with the following:

* A touch screen interface

* A choice of "views"-either 2d, which looks just like a map, or 3d, which looks a little more realistic

* All of these devices auto-calculate your route to your destination. Usually you can choose between shortest or fastest route

* Come pre-loaded with maps. Even most of the base price units have maps of the lower 48 states

Upgrades

Popular upgrades are:

* A wider screen, 4.3 inches diagonally as opposed to 3.5 inches

* Saying the names of the streets, instead of just saying "turn here."

* More maps

* Bluetooth integration for hands-free calling

* Real-time traffic and weather

* Millions of POIs, instead of a few hundred thousand

* Multiple route calculation

Price Comparison GPS

GPS systems range in price from around $150 for base units to $1,000 for Garmin's top of the line Street Pilot 7000. You can get a lot of bells and whistles for $200 to $300.

Magellan's Maestro line currently runs anywhere from about $150 for the Maestro 3100, which has a 3.5 inch screen, maps of the lower 48 states, and about 750,000 POIs. The top of the line Maestro, the 4250, currently runs slightly more than $250. With the 4250, you get a 4.3-inch screen, maps of the U. S. and Canada, 6 million POIs, real-time traffic capability and Bluetooth.

Garmin's GPS receivers are comparatively priced. Their introductory model, the Nuvi 200 does about the same thing as the Maestro 3100, and runs about the same amount of money. Their top of the line Nuvi 770 currently costs slightly less than $600, but it has every feature imaginable-4.3-inch screen, more maps, huge POI database, says street names, real-time traffic and weather, Bluetooth, and much, much more.

The other main manufacturer, Tom Tom, has fewer models to choose from, but they make a great product and their prices are in line with Magellan's and Garmin's. Their base model, the Tom Tom One, runs slightly more than $150. Their top of the line model, the GO 920 has a 4.3-inch screen and all of the other features.

To learn more, your next step needs to be finding an informative website where you can actually browse, look at pictures, and compare models.