You may update the status of a task to indicate progress towards completion.  The following status' can be chosen from the drop-down menu:

• Not started
• In progress
• Completed
• Waiting on someone else
• Deferred

To edit the staus of a task, double click on it within the Tasks, Calendar, or My Day applications.  When you check the box next to a Task, it's status will automatically be updated to Completed.