I have an HP iPAQ 310 Travel Companion. Mostly bought it for its graphics quality. It has a 4.3" 800x480 screen and renders the topography (plus buildings in the bigger metro areas) in 3D. It also comes with software to install on your PC so you can plan out a trip and multiple stops without having to tap it all in to the touch screen. It doesn't do live traffic info and it doesn't talk the street names (just "take the next left turn in 300 ft" and highlights the street name on the map). Not sure on the other brands if this is a common feature but it has an SD card slot and PMP functions so I can take it on the plane and watch videos on the really-nice screen instead of busting out my laptop. For what I wanted it works pretty solid.