Dan,
Yes Canada uses the same time zones, and even the dates of DST are generally the same. I'm talking about the date FORMAT (particularly what Windows refers to as the short date.) To me today is 2008-06-12. While this is not universally accepted as the standard format in Canada it is the ISO 8601 standard. This is primarily because dates can be sorted as text when displayed in this format, and in general quantities are given with the larges unit first (e.g 12 lbs, 6 oz.)
This setting (in Settings>Regional and Language Options) affects how a date is displayed (in short date format) throughout windows. It affects the format of dates in any application that taps into the Windows default format.
Clearly the format that I chose to display dates in should not affect the function of the software!
Paul