Hi, Nik. Using a PDA/GPS combo for your travels is a great idea and completely doable.
Not only does it eliminate the need for paper maps, but you can also use the handheld's PIM functionality to organize trip information, such as flight and hotel reservations, contacts for back home, and so forth. Typically, these devices come packaged only with maps of North America, but you can purchase extra software or SD cards for international maps, complete with detailed street maps and points of interest. I should warn you, though, that these maps can get expensive. (The good news is there are no fees to use the GPS technology once you've bought the device--here in the States or otherwise.) For example, with the Pharos Traveler 525 you mentioned above, you can buy the compatible Ostia Software for Europe for about $170 to $180, while some SD cards can run up to $400.
Alternatively, if you don't need the PDA functionality or you plan on doing a bit of driving around Europe, I'd also suggest taking a look at the Garmin Nuvi 350 or 360, the Mio C710, and the TomTom GO 910, which all have some great travel-friendly features, such as preloaded maps of Europe, foreign-language dictionaries, and multimedia functionality.