Similar to questions in the roadtrip software planning thread, I'm curious about portable GPS units that are designed for on the road navigation. There are several all-in-one units on the market in the $500-800 range that seem to be quite good, but I'm not sure I'm ready to pay that much for a navigation unit.

I have used a laptop with Delorme Street Atlas USA software and the Delorme Earthmate GPS receiver, but the laptop is bulky, requires a DC/AC inverter for constant power, and just isn't suited to use in a car like the compact GPS units are.

Delorme also makes Street Atlas USA software for handheld PCs and PDAs. Because I already have the Earthmate GPS and the software for handhelds is only $40, I thought a more economical route would be to buy a used PDA with color screen to replace the laptop. The only concern that I have with using a PDA is the amount of memory. I'm afriad that the PDA will not be able to store all of the map data necessary for a long roadtrip.

Do any of you have experience with the handheld version of the Delorme (or other brand) software? What are the limitations compared with the all-in-one units made by Garmin, TomTom, and Magellan? I look forward to hearing your experiences. Thanks!