move preprogrammed sd card to microsd card

It's nice to see Wallace and Gromit visiting the Factory

Sorry, though, preloaded maps from Garmin are not transferable to another SD card--they are tied to the specific card purchased from Garmin. Your best bet is to offer it on eBay or something similar, then buy the new map on a micro SD card, assuming that you prefer or need to have maps on cards that can be transferred between GPS devices (rather than installing to the nuvi's internal memory).

Here are some examples of recent eBay offerings (those in green sold while those in red did not sell). Prices will vary depending on the version of the map you have with new maps commanding the premium price. When I looked, I saw one 2010 map that sold for $40 + $5 S&H:

http://completed.shop.ebay.com/i.html?rt=nc&LH_Complete=1&_n...

It's likely that you can find the map on a micro SD card on eBay at a discount compared to Amazon, Garmin, etc. Just make sure the seller has great feedback, that you're buying a genuine Garmin-produced map on a card--and of course, that you're bidding on or buying the map on the correct micro SD!

Just DL the map to a micro SD with the adapter.

I have a similar issue. Own Garmin's Language Guide on SD card. I can't copy the contents on to a Micro card to use in the 3790. Any ideas of how to accomplish this would be appreciated.

Given that the OP is a US poster, I assume the GPS has an internal City Nav. North America to which has been added the Europe map with the Garmin SD card for a past and upcoming vacation. If true, that map won't work anywhere except with its original Garmin-produced SD card--or have you found a way to have one work in a different SD card? If the map is on a Garmin SD card, it won't be on the OP's computer's Mapsource either.

Oh never mind... I have no idea how I managed to misread this post, but I'm a dork. And, wrong.

The original sd card has an id number.
If the SD card is inserted on the Nuvi from the main screen of the nuvi, hold the top right part of the screen for 10 seconds until you see the debug menu. Page through 3 pages and you will see the SD card test menu and that page gives you the SD Card ID. That id number is directly linked to the GMAPSUPP.UNL file which should be on your sd card, opens with notepad btw. It's a Garmin security thing. Means the files must stay with the sd card. I have no idea why you cannot use an adapter to copy those files onto the micro sd card, I did that. In any event it would not do you any good, your 3790 will not recognize those files.

You could be on a roll here.

Rollin', rollin', rollin'... keep those doggies rollin'...

win32diskimager may work?

https://launchpad.net/win32-image-writer