Q: When I change the setting “Automatically adjust for clock for daylight saving time changes” at the dialog box Date and Time Properties”, the modified datetime does not change.
A: Are you trying to test if the Daylight Savings Time works in your computer?  Previously DST started on First Sunday of April so it would have been on April 1, 2007.  With the new law change, DST will start on second Sunday of March (March, 11, 2007)