Excel 2007 counting of earliest and latest time

HI
Is it possible to figure out the time difference between two times when I have date with the cell:
15-10-2009 10:40:23

I have more time information within the times I have to calculate where it is the time difference between the first time and last time I need:
19-11-2009 07:16:24
19-11-2009 10:43:40
19-11-2009 20:51:18
19-11-2009 20:51:35

In advance many thanks