I have dumped my Opera / Outlook combination for my web apps on the new laptop and have gone for the following OSS alternatives.
I have used mozilla a lot in the past (but not firebird), and opera was starting to get on my nerves with random crashes etc.
The beauty of using Mozilla Calendar though, is that it follows the open calendar format released by Apple with iCal. This means that I can subscribe to any iCal calendars I find on the web. Mozilla Calendar also allows you to publish your own calendar to an FTP or WebDAV server just in case anyone wants to keep in touch with your whereabouts.
So, now I am sorted! If anyone wants to subscribe to my calendar then click this link.