Excel question

I need to compute the number of work hours available between two dates. That is the easy part ... using the existing excel functions, but I need to use these numbers automatically in a staffing profile.

For example: I can compute the number of hours available between 15 feb 2001 and 22 aug 2001 fairly simply, but I then need to split out the hours in feb, the hours in march, the hours in april, ... etc. etc. and put them into an array that I will then chart to show a staffing profile. I need to do this for a series of dozens of tasks that spread across the next 7 or 8 years, some only a couple of months long, others a year or more.

Anyone have any idea how I can get this to work?

Joe