If you do a lot of business with a person or company that is in another time zone, I think you will find that having an alternate time zone shown on your outlook calendar takes some of the mental calculations out of scheduling a meeting.  For example, I currently have my calendar show both Eastern and Central time zones, as shown below:

To configure Outlook 2003 to utilize this feature, perform the following steps:

1) Select Tools, Options to display the Outlook Options dialog box:

2) Click the Calendar Options button to display the Calendar Options.

3) Click the Time Zone button to display your Time Zone configuration:

4) The Current time zone group shows time zone information for your current location.  When you check Show an additional time zone, it activates a secondary time zone.

5) Set the Label to the value that you would like displayed on your calendar.

Note: Keep it short.

6) Set the Time zone for the additional time zone you wish to add to your calendar.

7) Check Adjust for daylightsaving time should you wish that option turned on.

8) Click OK until you're back to the main Outlook screen.

That's it.  When you now view your calendar, you'll see the additional time zone shown to the left of your current time zone.  As I mentioned earlier, this feature is really useful should you need to quickly determine the local time for a person that may be on the other side of the planet.