The 305 is compatible with Garmin Express. If you haven't already, please ensure that you are using the most current version by following the link below:
http://connect.garmin.com/en-US/start/
Puzzled by the reply above. The link posted above forwards you to a page with a special link for 305,405 etc users that takes you to a general help page. Albert, are you saying that we can ignore this special link and use the 'Download for Window' option now?
I have also uninstalled all other Garmin software. That is, Express is currently the only Garmin software listed in Windows Control Panel / Programs and Features.