[excel] Excel date to Unix timestamp

To make up for the daylight saving time (starting on March's last sunday until October's last sunday) I had to use the following formula:

=IF(
  AND(
    A2>=EOMONTH(DATE(YEAR(A2);3;1);0)-MOD(WEEKDAY(EOMONTH(DATE(YEAR(A2);3;1);0);11);7);
    A2<=EOMONTH(DATE(YEAR(A2);10;1);0)-MOD(WEEKDAY(EOMONTH(DATE(YEAR(A2);10;1);0);11);7)
  );
  (A2-DATE(1970;1;1)-TIME(1;0;0))*24*60*60*1000;
  (A2-DATE(1970;1;1))*24*60*60*1000
)

Quick explanation:

If the date ["A2"] is between March's last sunday and October's last sunday [third and fourth code lines], then I'll be subtracting one hour [-TIME(1;0;0)] to the date.