As a co-worker pointed out, Microsoft stores time zone information in two places,

  1. HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Time Zones
    this is where the time zone database is stored.
  2. HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\TimeZoneInformation
    this is the current time zone information is stored.
    ie. the time zone information Windows is using currently.

Simple once you know.  And you do need to know this, if you are ever unfortunate to have to deal with Daylight Savings changes.

How to configure daylight saving time for Microsoft Windows operating systems
How to tell what Microsoft Time Zone you have