nicatnite303:
Have a look at this- http://support.microsoft.com/kb/928388/en-us
From the article:
The update that this article describes changes the time zone data to account for the United States DST change. This time zone update will also include changes for other related DST changes, time zone behavior, and settings. Some of these changes will occur in 2007, and some have occurred since these versions of Windows were originally released. The update that this article describes also includes some changes that have previously been released as individual hotfixes. An example of this is the Sri Lanka change in time zone offset. This update will also include some changes that have been individually documented in Microsoft Knowledge Base articles.