I am so sorry that when we were writting the book Treo did not support Windows Mobile 5.0.
My guess is that you will probably have to stick to CE5.0 to take the full advantages of the touch screen and button controls. But then you will lose the convenience (and the safety) of .NET CF.
Anothing thing you may consider is to take a look at the newer Windows Mobile 6.0 SDKs. Hopefully, one of the SDK may help you with your Treo 700.