I agree with beeclass on the antenna.
Keith, I think Tomtom (TeleAtlas engine) is really good in Europe but in America their map and routing engine is not as efficient as the Garmin (NAVTEQ engine). I have a friend of mine who bought a Tomtom and sometimes in Montreal the GPS tell him turn into a one way street but on the wrong side.
Here is a very nice long review from the "GPS magazine"
gpsmagazine.com garmin_nuvi_250
Go to page 5 for the difference btw both engine in America ...
D