I know what you want to do, and it's not possible the way you're explaining it. The zaurus pda's will run pretty much anything you can run in backtrack, just slower, so I don't see how they are limited. Like everything, there's pro's and con's to any hardware device.
No cellphone tower provides gps signals. The cell towers can triangulate your phone's position, if there's enough towers around you, and there's enough signal. It's a pretty rough location. My first gen iPhone usually put me about a half mile north of where I'm currently sitting. Sometimes it was within a couple houses in bigger cities, but nowhere near accurate to pinpoint a wifi access point. You really don't need gps anyway. I've located rogue access points in multistory buildings with just the zaurus and a directional antenna. Cisco makes a software platform that uses their wifi access points to do inventory tracking within a building. You get better results with more than three access points, but it can locate the devices within a ten foot radius.