In August of 2005 the United States Congress passed the Energy Policy Act, which changes the dates of both the start and end of daylight saving time (DST). When this law goes into effect in 2007, DST will start three weeks earlier (2:00 A.M. on the second Sunday in March) and will end one week later (2:00 A.M. on the first Sunday in November) than what had traditionally occurred.
Read this article (preparing for daylight saving time changes in 2007) to see how you are affected
I hope that you are not running NT4
Here are some direct update links
Windows XP
Windows 2003 Server
Full List
Microsoft products affected by the DST legislation
Windows Client
Windows Server
Windows Mobile
Microsoft Windows SharePoint Services
Microsoft Exchange Server
Microsoft Office Outlook
Microsoft Dynamics CRM
Microsoft Biztalk Server
Microsoft Entourage