For todo-list stuff I have gone through different phases. I started with MLO (my life organized). Then I found toDoList which is way better in every aspect (see my
review here:
academic productivity » Download: toDoList (Windows))
Then I realized that I have plenty of hard deadline tasks, and that I really needed a calendar integrated. For that, the best tool I found is agenda at once:
academic productivity » Programs: Agenda at once
Hope this helps...