The following regular expression can be used to match the above pattern
\d{2}/\d{2}/\d{4}\s+\d{2}:\d{2}\s+(AM|PM)
Expresso is an excellent to tool to make and test regular expressions. Some ready made regular expressions are also given in that program.
It is free and can be downloaded from here
http://www.ultrapico.com/Expresso.htm[
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I think it will be useful to you.