More and more businesses, ourselves included, are saying farewell to Microsoft Exchange and switching to Google Apps For Business - Gmail.
Google make a tool for migrating your Exchange data to Google Apps, the Google Apps Migration For Microsoft Exchange, known romantically as GAMME.
Getting it to work is the real trick though. Google have left out one little thing...
It won't work unless you have Microsoft Outlook installed.
It would have been nice if somewhere Google had of mentioned that. Maybe in the download page for the application, or even during the installation of the application, or MAYBE the error messages that arise when Outlook is missing could simply say "Outlook is missing". Instead, this is the message it gives you:
Please check if source server name (and authentication if applicable) and the list of specified users are valid.
Install a copy of Outlook on the same machine that is running GAMME (this is considered a bad thing to do on the Exchange server itself, but who cares? You are getting rid of the Exchange server anyway aren't you?).