Hi John,
You can create a new view that uses either or both of those fields as a sort field. Here is what I did to validate.
1. Create a new tab (I called it "Important")
2. Apply a basic view (I selected To Do > Active Actions) - this got me the layout I wanted, active tasks with no hierarchy
3. Click Filter to pull up the filter menu (it is in the bottom left of the screen)
4. Scroll down to Group and Sort and click Sort
5. In the "Sort tasks by" select "Importance" and the "Descending" radio button. This will put the most important at the top
6. If you want, click the second sort and select "Urgency" and "Descending".
7. Click OK
8. Click Save View and name it
I hope this helps,
Elizabeth