In updating the maps for an old StreetPilot GPS, I realized you can use a 276 or 376 as a USB card reader. The old StreetPilot only has a serial port and will transfer map data at a very pokey 38K baud. Almost 3 hours for 16M. 128M could take several days! I put the memory card from the StreetPilot into the 276, connected it via USB to my PC and transferred the maps. Much faster! Since this map data (MetroGuide) isn't locked, I just put the memory card back in the old StreetPilot and the transfer is done. Minutes instead of hours. This can also be useful if your PC only has USB ports and not the older style serial ports used on older Garmins. Happy updating!