|Just a friendly posting tip...|
A more relevant subject line would have included the word "percentage". If everyone in this forum used subject lines like Excel 2007 Formula Question then figuring out which thread was related to what issue would be impossible. It would also be very hard to search for specific issues in the archives.
That said, have you looked in the Excel Help files under Calculate Percentages? Excel 2003 offers suggestions for at least 5 different percentage related calculations.
Take a look and see if one of them fits your needs. If not, come on back and we'll see what we can do.