The most recent cumulative updates to daylight saving time (DST) and world time zones (TZ) for Windows are now available for supported versions of the Windows operating system. The cumulative updates have been released to the Microsoft Download Center and Windows Update..

These updates support versions of Windows XP, Windows Server 2003, Windows Vista, and Windows Server 2008. For information that details the changes in the cumulative updates, visit the following Microsoft Web site: KB 955839, December 2008 cumulative time zone update for Microsoft Windows operating systems

(More details are available now at http://support.microsoft.com/gp/dst_hottopics.)

Consumers and small businesses may want to use Microsoft Update to download and install updates that are available from Windows Update or wait for the latest update to automatically install on your computer via Windows Automatic Update.
For more information about the service that is provided by Microsoft Update, visit the following Microsoft Web site:
http://www.microsoft.com/protect/computer/updates/mu.mspx

System administrators and IT professionals may download the latest packages for distribution to their users.

Microsoft product teams follow a semi-annual DST and TZ update schedule, which follows the Windows regular schedule for publishing newly legislated DST rules and time zone updates. These annual "Cumulative Daylight Saving Time and Time Zone Updates" will be released in November/December for the coming calendar year; a semi-annual update will be released in July/August, as needed. Other Microsoft products that are affected may also schedule updates to accommodate some of these changes. For the latest DST updates on each of these products, please visit the following Microsoft Web site:
http://support.microsoft.com/gp/dst_prodlist

For more information about all the DST and TZ updates that have been made to date, visit the following Microsoft Web site:
914387 How to configure daylight saving time for Microsoft Windows operating systems