I have imported a heap of date from a crystal report and in excel i get dates and times as follows:

19/10/2012 3:35:00AM 19/10/2012 4:04:00AM
22/10/2012 3:50:00AM 22/10/2012 4:20:00AM
23/10/2012 3:50:00AM 23/10/2012 4:19:00AM
24/10/2012 3:38:00AM 24/10/2012 3:57:00AM
25/10/2012 3:24:00AM 25/10/2012 3:54:00AM
26/10/2012 3:38:00AM 26/10/2012 4:11:00AM
27/10/2012 5:35:00AM 27/10/2012 6:04:00AM
28/10/2012 6:40:00AM 28/10/2012 7:09:00AM
29/10/2012 3:39:00AM 29/10/2012 4:09:00AM
30/10/2012 4:03:00AM 30/10/2012 4:31:00AM

I need to convert the time from the text cells into Excel time so I can graph the time differences.
Can anyone offer a simple way to do this as i have mountains of data.

Cheers, Matt