Windows Vista has very cool feature, you can add Additional clocks to the task bar show up when you mouse over the clock you can show up to Two Additional clocks that makes it easy to track the time in different zone.

1. Right click on the clock in the task bar and select Adjust Date/Time.

2. select the Additional Clocks tab

3. Check the box Show this clock you can choose to select only one or the two clock if you want

4-select the time zone you want for this clock then give it name

Now when you mouse over the clock in the task bar you will see the Additional clocks