As a co-worker pointed out, Microsoft stores time zone information in two places,
- HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Time Zones
this is where the time zone database is stored.
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.