Calculating the difference between dates

Hello All,

I wonder if anyone can help me, i am really struggling with this one! Basically i want to be able to take the received date/ time and compare it to the current date/time and give me a output of the difference.

E.g.

Receive Date - 07/07/2010
Receive Time - 15:46:07

Current Date - 12/07/2010
Current Time - 19:16:37

Difference Between - dd/mm hh:mm

This may seem simple for one but i have over 10,000 of these to check, i am currently doing the following:

In one cell i add up the receive date/time to give me it in one cell. In the next cell along i do =NOW() and in the next cell i minus the =NOW() cell from the cell i have put the receive date/time together.

It doesnt seem to quite work, it doesnt seem to be able to calculate it when the difference between is less than a month, it puts it as 1 month and blah blah blah hours. I am really confused.

Ignoring what i have done or not if the case, can someone come up with a solution as it will make my life soooo much easier at work.

Thanks,
Matt