Excel graphing of dates and times?

Excel formula question. How do I graph a series of different dates and times, overlaying them on a 24 hour graph that will show a scatter chart for each event? The dates/times are in the following format: “5/13/2010 23:45:14”, “5/14/2010 4:57:40”, “5/14/2010 10:11:09”. The point is to use the event history to show the busy times of day. Thanks.