In many countries, the start dates and end dates for daylight saving time (DST) change from year to year. Additionally, countries may change their policy of recognizing daylight saving time, or they may change the local time offset from Coordinated Universal Time (UTC).
Daylight saving time implementation varies from country to country. Some countries may not observe daylight saving time, whereas other countries may change the start dates and end dates for daylight saving time every year.
How to change your computer's time and time zone in Windows Vista
How to change your computer's time and time zone in Windows 2003 and in earlier versions of Windows
How to change the time zone in Microsoft Office http://office.microsoft.com/en-us/outlook/HP052432171033.aspx
For more detailed information, please find this article which describes how to update a Windows-based computer to use the latest global time zone rules as of December 2007.
The following list shows some of the major changes that have occurred for daylight saving time:
• Argentina: DST is being introduced in Argentina.
• Brazil: There are different DST dates in Brazil.
• Canada: All provinces in Canada that use daylight saving time have adopted the same changes as the United States.
• Chile: There are different DST dates in Chile.
• Egypt: There are different DST dates in Egypt.
• Iran: DST is being reintroduced.
• Iraq: Iraq no longer observes DST.
• Israel: There are different DST dates in Israel.
• Mexico: Mexico has not adopted the DST changes that were made in the United States. Therefore, separate time zone definitions must be used for Mexico.
• Morocco: DST is being introduced in Morocco.
• Pakistan: DST is being reintroduced in Pakistan.
• Sri Lanka: The local time offset has changed from UTC+6:00 to UTC+5:30.
• United States: Beginning in the spring of 2007, the start dates and end dates for daylight saving time (DST) will change to comply with the Energy Policy Act of 2005. DST dates for 2007 in the United States and Canada 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).
• Uruguay: A new time zone has been created for Montevideo, Uruguay.
To obtain the list of time zones that have changed together with their DST start dates and end dates, use the information in the following Knowledge Base article:
942763 December 2007 cumulative time zone update for Microsoft Windows operating systems