Open your Outlook after you've installed 'TaskToCal'. First of all you will see a reminder that you use a trial edition if you didn't buy TaskToCal already.

After the first start you have the opportunity to add your existing Outlook tasks to your Outlook calendar.

Click on 'Yes' if you want to transfer your existing tasks to your Outlook calendar.

Now you see a new toolbar in your Outlook:

TaskToCal itself works in the background without any user interaction.

Let's look at an example:
You want to call a client on 1/8/2009 at 10:00 AM. Create a task with the reminder at 10:00 AM.

If you save this task then a new appointment will be created in your Outlook calendar:

What happens if you move your task in your calendar?
Move the task-appointment to 1/7/2009 8:00 AM:

The changes are reflected in your task, too:

This quickstart should show you how transparent TaskToCal works.

"TaskToCal" runs on Windows 2000/XP and Windows Vista with Outlook 2000, Outlook 2002 (XP), Outlook 2003 and Outlook 2007.

"TaskToCal" costs only 19.95 USD (includes 1 year free upgrades)