OK, seems I wasn't clear enough. There is indeed plenty of stuff available for planning - I am talking in-flight. Wasn't that obvious when I mentioned collision avoidance and early ground warning? IO540, you had better read all of the text before smiling about laptops.
The idea is indeed to have as much functionality as possible in as few boxes as possible. As mentioned, finding a suitable yet affordable display is a major hurdle.
And it is a basic requirement that all software and data should be freely available - which precludes Windows. The price for using free data is that it could never be certified.
@Justiciar: what difference between software for the USA vs. Europe? Temp's in °F and that kind of fun, but basically I can see no differences. Again: getting the data in a useable format, and keeping the data up to date is the real challenge.