If you are interested in handheld gps systems take a look here If you own a fairly new PDA you can use a search enging and find attachements that will give it gps ability. As for where to put it, I suggest checking out bugman's website and click on the radar detector link on the left hand side. That is what I plan on doing with my Garmin GPS 72.
Hope that helps. Feel free to pm me if needed. I used to be a navigation ET on submarines so I've worked with a gps a bit.
I just picked up a Garmin Forerunner 301. I plan to use it for keeping track of lap times on track and see the routes of my many rides. It's ment to be used as a way of training when running or biking; though I think it will work great for what I want.