I use the Garmin eTrex SUmmit which is the same as the yellow but has the altitude facility. I use it with Memory Map and only to record my walks from Garmin to MM. Earlier this year I upgraded my computer (desktop) and could not use the serial port so bought a USB converter cable which the computer recognised but not the Garmin. Explained this to Garmin and they e-mailed back a solution which worked for me. It is quite lengthy but I give it below and hope that it will help somebody.
If you have attempted to use the USB to Serial Converter cable, and it is not transferring data properly, the drivers for the device may not be installed correctly. Please follow these steps to check for proper installation:
1. Click the Start button
2. Right-click My Computer
3. Click Properties
4. At the top of the System Properties dialog box, click the Hardware tab
5. Click the Device Manager button (on Windows Vista and 7 simply click Device Manager)
6. From the Device Manager list, click the Plus Sign (+) next to Ports (COM & LPT)
7. Under the Ports (COM & LPT) heading, “USB to Serial Converter” should be listed followed by a (COM number).
a) If there is a Question Mark (?) or Exclamation Mark (!) next to “USB to Serial Converter” or it does not appear under the Ports (COM & LPT) heading, the drivers are not properly installed.
b) If there is not a Question Mark (?) or Exclamation Mark (!) next to "USB to Serial Converter" followed by a (COM number), it is properly installed
If the USB to Serial Converter cable is not installed properly follow the instructions that came with the cable to install the drivers.
If it is properly installed however MapSource does not recognize the unit you may need to configure MapSource to correctly see the GPS unit.
1. Open MapSource
2. Click Edit
3. Click Preferences
4. Select the Transfer tab
5. Select Search for Garmin Devices on the following serial port
6. Select Auto from the drop down menu
If Auto does not work try the specific COM port the unit is on.
If it is properly installed, but will not transfer data, there may be a software program preventing the serial/COM port from being used.
Make sure that your GPS is set to communicate in Garmin Mode. See your user's manual for specific instructions for your GPS unit. Then try the communication again. If it still will not transfer data, you will need to exit out of any programs running in the background that can use a serial port. One way to shut down unnecessary programs on your computer is with the Task Manager. Please follow these steps:
1. Open the Task Manager dialog box by pressing the keyboard shortcut: Ctrl+Alt+Delete keys.
2. Click the Processes tab.
3. Click the first column heading labeled Image Name to alphabetize the Processes list,
4. End Process on items named Hotsync, WCESMgr, wcescomm, UPS, X10net, Lvcomm, BBDVMonitor, BESMonitor, Parachute, Weatherpak, Zune, Sidekick Mojo, Intercept and Tablet.
5. Click Yes to the WARNING message.
NOTE: These programs will automatically start again every time you start your computer.
6. Retry transferring data with your GPS unit.
If these procedures do not resolves the communication issue, try a different USB to Serial Converter cable produced by another manufacturer to see if it will transfer data properly.
If you have no serial port on your computer and the USB to Serial Converter cable attempt has failed, there may be another solution. You can purchase a Serial PC Card Adapter for laptops or Serial PCI Card for desktops, to give your computer a true serial/COM port. These can be purchased through some Internet online retailers, or most computer/electronics retailers. When purchasing any hardware for your computer please make sure that it had the proper drivers for your Operating System especially when it is a 64 bit version.
If there is anything else I can help you with then please let me know. Alternatively you can search for a solution here:
http://www.garmin.com/support