Hide results of repetitive formulae if one variable is blank?

I have a simple table set up in MS Excel 2002. The table has 3 columns, date, payment amount, balance and about 20 rows. In essence, all I want to do is enter the date and payment amount and see the balance automatically adjust. So I set up a formula at the top and dragged it down the 'balance' column. However the current balance displays itself all the way down, even when the adjascent 'payment amount' cell is empty.

How can I hide the value in the 'balance' column until I enter a value into the 'payment amount' cell?

Any help is much appreciated.

Fantastic, thanks for that.

Can you suggest a place, on this site or elsewhere, to run through a few tutorials on this kind of work. I have just started a new job where it seems excel will be one of the main tools.

Thanks.