The "patch" also changes past history for all MS-OSes other than Vista. It applies the new start/end dates for DST to all years, so historical data for programs that use the operating system to calculate date/time will change as if the 2007 DST rules were in place. This is REALLY messing stuff up!
Micro$oft's techie answer can be found here:
To retrieve accurate historical DST values, you must create your own implementation that understands the adjustments required and can manipulate the underlying Windows date and time information.