@Islandman
I seem to recall that you also have a 26x0 streetpilot so it seems you've taken the 26x0's CF card map named "gmapsupp.img" and renamed it "gmapprom.img" to flash to your 2720, correct?

The syntax is correct as you've written it in the post above (i.e. "C:\Garmin\WebUpdater\WebUpdater.exe /upload_file rgn=49 path=C:\Garmin\gmapprom.img -autorun usb /i"), so both the BAT file and the command prompt should work provided that all files are present and correctly placed. Something must be wrong to get the massage about not finding the path. What exactly do you have in the C drive's Garmin folder? Post a screenshot if possible.