Outlook 2003 used to save the default reminder settings in the
registry, such as: HKCU\Software\Microsoft\Office\12.0\Outlook
\Preferences\RemindDefault.

However, although this key and value still exists in Outlook 2007, it
looks that Outlook 2007 actually save this settings in another place.
The value "RemindDefault" is synced to the other hidden value when
Outlook starts in a profile. In this way, Outlook 2007 can set
different values for separate profiles.

Does anyone know where Outlook saves this settings? Possibly some
hidden message in the message store...

Thanks for any information!

I have found it: it is saved in a hidden message
(IPM.Configuration.Calendar) in the default Calendar folder.