Excel graph date and count

I have a list of date+times and a count for each, eg:

Date/Time             Count
6/19/12 3:00 AM         1
6/19/12 4:00 AM         1
6/19/12 5:00 AM        79
6/19/12 6:00 AM       322
6/19/12 7:00 AM       275
6/19/12 8:00 AM       143

I would like to graph based on hour but when I select the data and graph it excel groups all the hours in the day together. I would like to see the trend as time passes. What do I need to do?

Format the axis as a Text axis - Excel wants to format it as a Date axis, which has a minimum resolution of 1 day