Events for PIM (Outlook) related events

Does anybody know if there is a way to catch events based on PIM related activities (saving items, marking to-do items as completed, etc.)? I'm working on an application that notifies and synchronizes when to-do items are created, marked as completed, or updated. Currently, I'm having to use the timer to perform a sweep of the to-do items. I really don't like having timer events running when they aren't needed most of the time.

Thanks.

You can catch several tasks related events with agraham's SystemState library.
See this page for the available properties / events: SystemState Members (Microsoft.WindowsMobile.Status)