Column A is either blank or has a date
Column B has a date
Coumn C has a person's name
I want return the person's name if Column D column A is blank or greater
than a certain date and if column B is less than a certain date

Example
Column A = 27/06/2009
Column B = 15/05/2009
Column C = John
Return John in column D if Column A is 31/05/2009 and column B is <
31/05/2009.

Any ideas please?