Sunbird was almost what I wanted, back in the '04 timeframe, but it seemed unstable. I lost some appointments when they never made it up to the server. I used C

Sunbird was almost what I wanted, back in the '04 timeframe, but it seemed unstable. I lost some appointments when they never made it up to the server. I used CalDAV with Sunbird using a DAViCal server. Sunbird was abandoned. I haven't looked recently to see if there's a reasonable replacement that might run on Windows.