As I mentioned earlier -- and just in time for the upcoming changes to daylight saving time that affects many products and services -- we have a newly renovated DST 2007 website. (http://www.microsoft.com/dst2007 in case the hyperlink fails.) My posts sparked this question from a reader:

"When I travel, I just change the clock in the Control Panel. So shouldn't I just change the clock when the new DST rules kick in?" 

No, no, no...

First off, for current Windows XP systems, an update is available for your computer for machines that subscribe to Automatic Update. So your PC will automatically compensate for the new DST changes. (The exception to the rule: older computers with Windows 95/98/ME, where you may choose to not use DST and manually set the clock on the new DST 'spring forward' and 'fall back' dates.) 

But when you travel, you should change the time zone to the city or area (or country) you're visiting. If you just set your system clock to the local time, then your actual time will be off (not to mention the jet lag).

For example, let's say I'm in Redmond, and I fly to New York. My PC is normally set to the Pacific Time Zone (which is GMT -8:00hrs). the Pacific Time Zone (which is GMT -8:00hrs). If I just set my clock to the local time in Manhattan (by right clicking on the clock display, or through the "Date and Time Properties" control panel), which is three hours later than Seattle (GMT -5:00hrs), my clock will appear correct but I'll be three hours late for all my meetings because my time zone is still set to Pacific.

What's worse, let's say it's 11:00pm Pacific when I make the change: if I move the clock ahead to 2:00am and don't adjust the date, by clock will be a day behind as I've adjucted the clock before the date advances.

If I set just the time zone to Eastern, then all will be fine: my clock will be correct for NYC, and any meetings I have on my computer (or that I schedule in Outlook) will be correct. Here's more help and tips on time zones, Daylight Saving Time, and e-mail in Windows XP. Now, that won't fix being late for meetings due to other reasons...

The Office team has a good article describing how to use and set time zones here -- you can not only adjust your master time zone when you travel, but you can add a second time zone to be displayed in the Outlook 2007 calendar (handy if you work regularly with a particular international city). From the article...

Dual time zone"You can add and display a second time zone in Outlook, which can be useful when you are scheduling meetings or conference calls with people who are working in other time zones. When you add a second time zone, the current time in the primary time zone is highlighted with a color gradient to make it easier to see.

"If two time zones are shown, the meeting organizer's time zone is used as the reference point. If you organize a meeting and display free/busy time for invitees from other time zones, their busy times are adjusted so that they are displayed correctly in your time zone. The second time zone is visible only when you view the calendar in day or week view."

 

The article also notes that start and end times for Outlook Calendar items are stored in the Coordinated Universal Time (UTC) format... I've heard people refer to GMT, UT and UTC all as the same thing, but they're not. Interestingly enough, it's Universal Time (UT) which replaced GMT, not UTC. Somewhat depressing, as I enjoy listening to the broadcasters on BBC World News (on NPR, often on my drive home) talk about the current time in GMT: "UT" just doesn't create the same feeling. ;)

This from the Wiki...

"(UT is) a timescale based on the rotation of the Earth. It is a modern continuation of the Greenwich Mean Time (GMT), i.e., the mean solar time on the meridian of Greenwich, England, which is the conventional 0-meridian for geographic longitude. GMT is sometimes used, incorrectly, as a synonym for UTC. The old GMT has been split, in effect into UTC and UT1."

More information:

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