In a nutshell you are SOL without extended support.
Microsoft calendar software such as Outlook depends on the operating system time zone information to display time information. However, Collaboration Data Objects (CDO)-based programs such as Outlook Web Access depend on separate internal time zone tables. This update modifies these internal time zone tables to match the changes in time zone settings.
Without this update, calendar items in CDO-based programs will operate as if standard time is in effect during the extra weeks of daylight saving time. For example, without this update CDO-based programs will operate in standard time during the following periods in 2007:
? March 11, 2007 through April 1, 2007
? October 28, 2007 through November 4, 2007
See http://www.microsoft.com/windows/timezone/dst2007.mspx for more info.