What is a reasonably priced accessory to turn a laptop to a car navigator usable in both US and Europe?

For one that also includes Europe, I don't think you'll find one reasonably priced. I recommend getting away from using your laptop for serious navigation. Laptops are ok for plotting routes and finding places, but for on the fly real time navigation in both The US and Europe, I have to recommend the Tom Tom. Check it out at Best Buy or the link below.

I ran Microsoft streets and trips for 5 years on my laptop with GPS, and it was very hard to manipulate the program while driving if I needed to for an alternate route or something. The new Tom Tom is just great. I love it.

Ps. Check out some of their other things for laptops and PDA's you might find what you need. Good luck.

something compatible with your opperating systems;i.e.tom.tom.(research required).not an easy task