Thank you guys,
I appreciate your answer. After checking all this, I think I will build my prototype with an old PDA like H3850. Cheap and easy to find. In addition I can target it with linux or WINCE. Full floating point support too.
The idea of a custom uC is on the drawing board too but if theres is no others choice. I would like to get full color display with good looking map. With easy integration. I don't want to rewrite a complete screen driver.
Seriously I will keep you inforrmed when I will get a working prototype
