At first glance, PalmOne's GPS Navigator add-on seems like an ideal solution for somebody who gets lost only occasionally.

A customer wouldn't need to spend thousands of dollars to add a navigation system to a car -- or hundreds to buy a dedicated Global Positioning System unit that may see little use. Instead, this compact, wireless-enabled pod works with the Palm handhelds many people already own.

Except things aren't quite that simple. First, the GPS Navigator not only requires a Palm with built-in Bluetooth wireless capability, it requires the right kind of Bluetooth-enabled Palm handheld. Of the four that PalmOne has shipped, only two, the Zire 72 and the Tungsten T3, are eligible. (Sony Clie handhelds aren't supported.)

You'll then need to pop an SD Card into a Zire 72 or Tungsten T3's expansion slot to store maps of your chosen area. PalmOne says a 64-megabyte card will do, but covering the entire Washington metropolitan area requires a 128MB card.

The simplicity of wireless navigation lasts only as long as the batteries in the Palm and the GPS Navigator -- about an hour and a half to two hours either way. You can power both units from your vehicle's electrical system using an included charger, but that adds wires and complexity to the whole setup.

Once installed, though, using the GPS Navigator is fairly straightforward. Put this device, about half the size of a hockey puck, on your car's dashboard and turn it on. The Palm uses its Bluetooth circuitry to pair up with the receiver -- it tells the Navigator to establish the car's position (using the signals sent down by the network of GPS satellites) and then crunches this data to draw maps and driving directions on its screen, reading out turn-by-turn instructions through its speaker in a synthesized voice.

The Navigator's software, developed by an Amsterdam firm called TomTom, provides a simulated view of your location as seen from above and behind your car, instead of the directly overhead perspective offered by most GPS units. This gives you a much clearer glimpse of what's coming up next -- even on a Palm's small screen.

The spoken instructions are clear and easily heard above a car's usual noises, even the radio. TomTom's software is smart enough to issue warnings about upcoming turns farther in advance if it sees that you're going faster.

Unfortunately, this bundle of hardware and software shows some weaknesses in extended use. If you drive past one map, you can't navigate to the next without stopping to load the next map. (The Navigator usually needs three maps just to cover the Washington area, although a single, all-encompassing map of this region is available.)

The software can't tell you on which side of the street an address is located, something other navigation products do with ease. This meant that every address was displayed in the center of the roadway -- not too helpful if you're rolling down K Street at rush hour.

More serious, some of the geographical information in the TomTom database is wrong. For example, when driving to a business on Gallows Road in Tysons Corner, the Navigator told me to turn north into the mall instead of south to Gallows. I found similar errors in the locations of roads -- some were off by hundreds of yards.

If you can overlook the errors -- and you've already anted up for the right kind of Palm and have a memory card handy -- this package might be worth the $300 it costs. Otherwise, you might be happier with one of Garmin's Palm-compatible GPS handhelds: Its iQue 3600, $589, was reviewed favorably in this space last August, and a newer, smaller version, the $536 iQue 3200, is due later this month. Online mapping services such as MapQuest can be used on many newer cell phones as well, although monthly charges can apply.

A good set of paper maps and the willingness to stop and ask directions might also suffice.

PalmOne's add-on offers GPS guidance for a little less.