Here's a simple sync.ico that users can put into the \windows directory on their Axims so that the Windows Mobile Device Center shows this icon.
Here's how to use it:
Unzip the contents of the x51v.zip file.
Move the sync.ico to the Windows folder on your Axim.
If the device is already configured, go to the Device Manager in Vista and delete/uninstall your Axim. On my Vista Ultimate system, my Axim is listed under "Portable Devices-->PocketPC".
Undock (if docked) and then redock. The system should copy the icon from the PPC to Vista and display it on the Mobile Device screen on your Vista desktop.
You can of course use this icon as you would other icons in Windows/Vista, say if you wanted an Axim icon for your local Documents folder.