Hi Marvin,
It's probably worth mentioning that the reason it's hard to find good coverage of Mexico is not entirely the fault of the folks at DeLorme or Garmin or Microsoft or Navteq, etc. There are many countries in the world that simply do not have all the streets and roads surveyed as we do in Canada, America and most of the western European countries. So it's impossible for the data gathering companies, like Navteq and TeleAtlas and DeLorme to get data that does not exist. In other cases, the data may exist but the authorities refuse to release it.
...ken...