You can save a couple hundred bucks by opting for one of the two most popular GPS-enabled mapping programs instead of a stand-alone GPS device, but you'll lose a lot of simplicity--and some accuracy--in the bargain. Both mapping products require either a laptop or a PDA for navigation.

When I took the shipping versions of Delorme's $150 StreetAtlas USA 2007 Plus With Earthmate GPS LT-20 and Microsoft's $129 Streets & Trips 2007 With GPS Locator out for a spin, I found both to be a few turns short compared with stand-alone GPS devices. In my head-to-head comparison of these software-GPS combo packages, StreetAtlas topped Streets & Trips, but not by much.

As in its previous incarnation, Streets & Trips requires you to click a button to generate a new route--not a good idea, since this means you must take your attention from the road as you locate and select an on-screen button.

StreetAtlas USA and every other GPS system I've tested recalculates routes without users having to take any action. So Streets & Trips' lack of automatic recalculation is reason enough for me to discourage you from buying the package.

Besides StreetAtlas's no-touch navigation, I was also impressed by the product's clear interface and the text-to-speech engine that pronounces street names. On other hand, this package never caught up with my exact location, informing me that I still had some distance to travel when I was already at my destination.

Lag was a problem with Streets & Trips as well. For example, the program warned me of a turn "five-tenths of a mile" ahead that in fact was just about 100 yards away. On an unfamiliar route, this imprecision could catch a driver off guard.

Both products initially locked onto satellite signals with ease (this was a great improvement over the previous version of Streets & Trips). With StreetAtlas's Earthmate LT-20 and Streets & Trips' SiRF III GPS devices connected via USB, each program acquired sufficient signals to plot my location in about 30 seconds initially, and instantly thereafter. Still, the gap between receiving the signal and the display of directions left me feeling like the programs couldn't keep up with me. And I don't drive that fast (honest, officer).

Both programs include applets for use with recent Palm OS and Windows Mobile PDAs (StreetAtlas USA's applet was formerly sold separately); the Delorme applet also lets you download static maps to Apple iPods and other photo-enabled media players. Delorme's free MapShare online service makes it easy to share your maps and driving directions by posting them to the company's servers and sending out e-mail invitations.

Streets & Trips benefits not only from the improved precision of the SiRF III GPS hardware, but also from links to the Windows Live Search and Windows Live Local services for finding up-to-date information for the area you'll be traveling in. However, neither Streets & Trips nor StreetAtlas was aware of a year-long, massive highway project nearby.

If you're looking for a budget GPS system and you don't mind balancing your notebook computer on your passenger seat, StreetAtlas USA 2007 is your best bet. The program can't match the clear maps, ease of use, or compactness of a stand-alone GPS such as the $499 TomTom One, but its ability to recalculate routes automatically and pronounce street names puts it miles ahead of Streets & Trips.