I would try windows 7, disable all notifications after properly configured. And try CF 3.5 for 30 days. Bluetooth does work with my iPhone 4, but it's not great (no contacts). Navigation is however iffy, to say the least. I don't use it.
But if navigation is important, and easy to use, try fitting a 7" tablet, like the Elocity 7, or the Galaxy Tab. That's the direction I would go.