Ken,
If you're interested in looking at a product like
Garmin's Mobile PC, which so far looks to be yards ahead of the others, I just discovered they have a new
Mexico map product.
If you look up in the upper righthand corner of that page you will see a small box that says
"MapSource Map Viewer". There's a link in there to
City Navigator Mexico NT. You can use that to browse the map online and see if it's what you need.
It looks like they've got that map linked to their older map viewer server so it doesn't always display the map when you zoom or pan so you have to refresh it once or twice to persuade it to display the next view. If you run into the problem please do take a moment to email tech support and bitch about it. They're probably tired of hearing about it from me.
The performance of the online viewer, and also the quality of the display, shouldn't deter you. Mobile PC looks absolutely gorgeous, even with my old Metroguide Canada maps from 2003 data. The online viewer is just to give you a way to check out the usefulness of the data it contains. When I zoomed in fairly tight in Guadalajara I could even see a whole bunch of Points Of Interest, like stores, restaurants, motels, gas stations, ATMs and so on. For what it's worth, I have a bit of a bias towards Garmin and they have confirmed it again with Mobile PC. Right now I have DeLorme's Street Atlas USA 2008+ and Microsoft's Streets&Trips USA 2008 on my laptop. I also have Garmin's nroute and Garmin's Mobile PC plus a bunch of Garmin's map products (for my Garmin iQue 3600 integrated GPS/Palm PDA). As I mentioned above, I think Mobile PC is better than the others for nav use. That's no surprise. The others have generally been trip planning products that have had navigation sort of tacked on. At least that's the way they feel. Garmin has been focussed on navigation - on land, sea and air - from the beginning, and it shows.
I hope this helps.
...ken...