Hey Bill,
You don't need to spend $600 for GPS for a bike. If you're willing to risk a $350 netbook on the tank, you should be even more comfortable with a $200 Garmin Nuvi type of nav device mounted on the bars or inside of the fairing. The Nuvi (TomTom, whatever) type of GPS would be quicker and easier to shove inside something when the rain starts. And it's lots cheaper if you manage to destroy it.
I have a Garmin Legend HCx that I use in a handlebar mount on my mountain bike (the sort with pedals ... uggghh). My buddy uses the same GPS and mount on his BMW 650GS and also on his RS. It's rugged and weatherproof and small enough to stuff in a pocket when you go walkabout.
If you want a computer thingy for the bike, you might consider the
Viliv S5 or if that's too small you could see if you could find a small tablet style laptop. The ideal thing would be something that would fit inside the transparent map case on the top of a tank bag .. you know, the place where we used to put the real maps?
...ken...