Thank you all for the responses, Catymag, dasilvarsa and ddabcd277

MapUpdater is at the latest, v3.1.14, downloaded by the update process at myGarmin just before the latest atempt to fix problems.

F:\Garmin\GarminDevice.xml says the device is a 37xx, not 3790. Should I update this manualy ?

I do have a clean, empty, 4GB microSD card.

Questions are:

1. how do I tell MapUpdater to install the map there ?
2. how do I move the map to the main memory, since I need a SD card to hold brazilian maps ?

And yes, Internet conections is a crap down here, specially the area where I live. This could have ruined the whole process.

Thank you ! Grato, amigo.