HELP!

I have been unsuccessfully trying to search column C in the following table for the first occurance of a value which is equal to or higher than a given value – the returned value to be the corresponding date in column A.

I also need to know how to do almost the same thing except searching column D for the first occurrence of a value which is equal to or lower than a given value – once again being presented with the corresponding date in column A.

I have experimented with various Lookup and Reference functions to no avail so far.
the first 3 rows of data in the table are:
***A************B*******C******D******E
DATE**********OPEN***HIGH****LOW***CLOSE
7/23/2005 1.206 1.2068 1.2055 1.2056
7/24/2005 1.2056 1.2087 1.2026 1.2059
7/25/2005 1.2059 1.2068 1.1979 1.2012