Do you know what, some time it plays to read a KB! I am sure you have checked out http://support.microsoft.com/kb/931667. Under “Why the Time Zone Data Update Tool is required” It says …
“Calendar items are created in Outlook by using Coordinated Universal Time (UTC) format. UTC is an international standard 24-hour timekeeping system. Time zone information for Outlook is obtained from the Windows operating system in which the calendar items are created and is obtained at the time that the calendar items are created.
For example, an 8:00 A.M. appointment on March 1, 2007 in Redmond, Washington is stored in Outlook as UTC 4:00 P.M. In this case, DST has not yet started, and Redmond time is eight hours behind UTC.
When an update is applied to the Windows operating system to accommodate the new DST definitions, the computer’s local time is changed to the extended DST time. However, the UTC is not adjusted when the local time on the computer is adjusted. Therefore, calendar items that are added to Outlook during the extended DST period are off by one hour. “
So by the sounds of it, you only need to use the tool on server that are in the affected time zone