Hi SkipVought,
Welcome to Laptop GPS World.
Is TabletPC better than an all-in-one PND for planning a route? Yes, the larger screen helps. Also, programs like
Microsoft Streets & Trips and DeLorme Street Atlas are both excellent trip planners for PCs, but they would not work on all-in-one PNDs (personal navigation devices).
As Ken says, the more clearer idea you have as to what the mapping/GPS software is going to be used for, the easier it will be to decide on the purchase. They all can bring you from A to B, but some may be easier to use than others, and some may not have the features your wife may benefit from.
Will she use it only as an aid to her driving, or will she also want to use it as a presentation tool to show her clients on the map where the houses are, what the neighborhood looks like, nearest schools, parks, and other amenities? Microsoft Streets & Trips and DeLorme Street Atlas could be suitable choice. If the usage is to be purely for her own driving, then the other available programs may be better, as they may be easier to use on the road since they have been designed to be a GPS navigation tool,rather than a sophisticated route planner and a desktop mapping application. Suitable choices would include Garmin Mobile PC, iNav iGuidance, ALK CoPilot, etc.
For mounting solutions for TabletPCs, UMPCs, and laptop PCs, visit
RAM Mounts website. I'd actually go as far as suggesting not to buy a TabletPC unless you can find a suitable mobile mount for the model of TabletPC.