Calculate a total holiday price based upon different nightly room rates

Hello

I really need some help here with Excel 2000 and hope someone can help.

I've created a worksheet of rooms (shown in columns) and nightly prices (shown in rows) per the attached copy of my worksheet.

I would like to create a facility where I can enter an arrival date (e.g. 04/04/12) in cell A20 and a departure date (e.g. 09/04/12) in cell A21 and, for each column, (or room) it shows the total price (e.g. 249 for column D, 264 for column F and so on and so on).

Any ideas ?

Thanks