Configure the date and time settings in Windows Vista
Windows Vista automatically displays date and time following the standard for your language (English US/Canada, English UK, English Australia, etc.)
It even takes care of automatically adjusting your system's time during daylight saving changes. How the date and time are formatted, however, is up to you; this tutorial shows you how to customize the date and time settings in Windows Vista.
Customize your date and time settings
To adjust Windows Vista's date and time options, right-click on the clock, and choose "Adjust Date/Time".
This will open the Date and Time window that controls how dates and times are displayed: most applications (programs) rely on your operating system's settings when it comes to displaying date and time.
Date and Time options tab
Under the first, "Date and Time" tab, Windows Vista lets you change the date and time of the operating system (a separate tutorial covers it).
Right below, you can change your time zone by clicking the Change time zone button: your time zone was set when you first installed Vista on your computer.
Checked by default, the "Remind me one week before this change occurs" checkbox instructs Vista to remind you that Daylight Saving Time is about to start or end.
Additional Clocks options tab
The second, "Additional Clocks" tab, allows you to display up to two other clocks (time zone), useful when you need a quick reminder of local time in other places. The Additional Clocks tutorial goes in more details.
Internet Time options tab
With the third, "Internet Time" tab, Windows Vista uses a remote server of your choice to maintains its time accurate. This is why Windows keeps resetting the time if you make your clock 5 minutes faster (unlike some older versions of Windows). To modify this behavior, and/or change the synchronization server Windows uses, click the Change settings button:
By default, Windows Vista periodically synchronizes your computer with the time of a remote server; to prevent this default behavior, simply uncheck the "Synchronize with an Internet time server" checkbox and click OK.
To immediately synchronize your time to make sure it is accurate, click the Update now button: this will use the selected server to update your computer's current date and time. Once you click OK, Windows Vista will use the last selected server to keep your date and time accurate.