[Mediawiki-l] how to set time zone?

[Gart, Mitchell]

Sorry for the newbie question but I did search the doc and archives
first.

I'd like to set the time zone.  I have done this

$wgLocaltimezone    = 'EST5EDT';

in LocalSettings.php and it didn't do anything.  I'm running 
MediaWiki 1.6.5 on Windows.  Can somebody tell me how to set it
correctly?  Thanks.