I purchased The Windows version of "Atlas speaks" several years ago and used it a great deal on my desk top computer no less. Although I think that putting GPS on a lap top would be a giant step backwards, I do think that there might be a market for the limited version to be put on a standard computer. The name escapes me, but I am thinking about the version that does not allow for GPS. It would be for those who would want to check out a route in vertual mode before or after walking the route.
As for R and D on this, though, I think time might be better spent on continuing development of the software on a cell phone. Now that is easily portable. I think the price would be less than that of a PDA plus the GPS software.
Joleen