Does anybody know: What brand SD card(s) does the Montana read? Read a couple threads talking about some not working. What size SD card do you need to hold city nav and a couple regions of 24k maps? I'm referring to the ability to load multiple map downloads for the Garmin disks onto a store bought SD card. Does city nav really cover all road paved and unpaved? How is city nav different from 100k maps? I really don't need/want turn by turn directions, just as many roads as possible, of all types. If I already loaded the rocky mtn 24k CD onto my Montana, can I still load it onto a SD or is it locked from being loaded onto another "device"? Thanks for helping a noob but there is a lot of info out there and I got many other questions answered but these or what remain for me... For now.