I agree, the Navteq (version 9) software covers nearly every single back road and lane way in the country.
I bought a Garmiin Nuvi 300 recently but when I purchased it, it still had the old version which was pure crap outside the major cities as it only showed the major routes. I was entitled to a free upgrade in the mapping software and although it took a couple of weeks for the update disc to arrive in the post, it was well worth the wait.