Both the TomTom One (left) and HP's iPaq rx5000 Travel Companion are small enough to slip in a pocket.Good news for travelers in search of compact, easy-to-use GPS navigation systems for their cars: TomTom, a leader in the category, has a new portable $499 device, while HP is introducing a $599 GPS- and Wi-Fi-enabled Windows Mobile handheld. Both units use the latest version (6.0) of TomTom's excellent Navigator software, both are svelte enough to slip into your pocket, and both are great at what they do. The TomTom One is a fine choice if GPS navigation is all you need, while the HP iPaq rx5000 Travel Companion is worth a serious look if you'd like a PDA as well. (Note: PC World reviewed the iPaq rx5000 shortly before the product's release.)

The shipping TomTom One is smaller than the company's previous entry-level product, the Go 300. The One isn't a lot taller or wider than its 3.5-inch touch-screen LCD, and is about just 1 inch thick. Because it's so small, you can easily take it along when you exit the car (instead of leaving it behind, where it could be an easy target for thieves or susceptible to heat or cold).

The One ships with maps preinstalled on a 1GB SD Card that slides into a slot on the device (the maps cover all U.S. states and Canada). Unpacking and setting up the unit, and getting going with it, took one of us only 20 minutes.

You have several ways to select a destination: by typing an address on the on-screen keyboard; by choosing a point of interest (POI) such as a hotel, restaurant, or attraction in TomTom's extensive database; by selecting a previous destination stored on the device; or by tapping a point on a map (which you can scroll in any direction by dragging it with your fingertip).

TomTom's software previews its calculated route for your approval, and then it switches to a 3D view that shows upcoming turns along with the distance and estimated travel time remaining until you reach your destination. In our tests the TomTom One proved accurate from a good 35 miles out.

Our only gripe with the software: Entering a specific POI can be tricky since you can't access the software keyboard once you have specified the city and POI category. You can type in a particular hotel or restaurant in a city only by choosing 'Any POI Category', as opposed to going through the logical 'Hotels' or 'Restaurants' categories--not an easy or intuitive approach.

We looked at a preproduction version of HP's iPaq rx5000 Travel Companion. Though nearly an inch wider than the TomTom One, it's still pocketable, as it's the same height, about half as thick (0.6 inches), and, at 6 ounces, one-third lighter. Like the One's, its touch-screen LCD measures a nice 3.5 inches.

TomTom's Navigator software and maps are stored in the HP's 2GB of ROM (leaving about 50MB for other programs and data, unless you expand storage via the SD Card slot); but as navigation tools, the TomTom unit and the HP share the same easy-to-use interface and snappy position tracking (your map reflects your actual location).

The Travel Companion is also a very capable Windows Mobile 5 PDA, with a 400-MHz Samsung processor, 64MB of SDRAM (for running applications), and integrated 802.11 b/g Wi-Fi and Bluetooth. HP has added some useful hardware controls, as well: A square rocker button to the right of the screen sets both voice volume and zoom level when you're in one of TomTom's map views; you can also use this button to scroll between and select menu options. Smaller buttons below it shut down Windows Mobile apps and launch the OS's main menu.

Unlike the TomTom One, the Travel Companion is on the pricey side compared with other devices in its class. But for only $100 more than the One, it adds quite a bit of functionality, and it gets extra points for sleek design.

Depending on whether you need a Windows Mobile handheld as well as an in-car navigation system, either product is well worth considering.