For that much I would get a cheap handheld like Garmin Etex basic. You can unplug it and use it by itself for outdoors. If your notebook has no serial port, you can buy a USB-comm converter.
Also, palmone.com current has a Magellan receiver for palm + open box palm 505 color for $137 after rebate. It is a good deal for street driving. Personally I do not want to haul a notebook along. It is much easier to afix the palm on the dashboard.