you got me on this one. I do have a garmin gps and just cross reference the coordinates with the gecko map. there is garmin software that you can pick up in the russian market. I dont have the detailed map in mine as I find it clutters the screen, but I do mark points as to find my way back to some neat things (and not to mention keep me from going in circles in some of those villages)
Ah. Apparently, you find whatever datum you're using matches up fairly well with the Gecko map, no? If at all possible, could you take a look at you Garmin and see what you're using? My unit's fairly simple as well, so I'd like to at least get a datum that's close(which yours is, from the sounds of it). Go to you setup menu and click on "units" and it should show which datum you're currently using.