I recently started using Kontact, and it's nice. One thing someone could have mentioned, though, is the fact that the birthdays saved in KAdressBook are not automatically used from the KOriganizer reminder daemon - of course not, KOrganizer is a different application. The Kontact integration got me fooled there - and I promptly forgot a lot of birthdays.
However, importing the birthdays to KOrganizer is really simple. Here you go:
1. Open KOrganizer (I did it through Kontact -> Calendar)
2. In the sidebar, at the bottom left, there's a box with resources (Usually the Default KOrganizer resource, ticked). If it's not there, go Settings -> Sidebar -> Show Resource View.
3. At the resources, click 'Add'. The KAdressBook birthdays are in the list. Select them and click OK. C'est tout!
