Microsoft Excel 2000 question...?

-I have 3 columns. The 1st two are numbers I will input each day moving forward. The 3rd is set to "AUTO-SUM" the 1st two columns. I've copied/pasted the 3rd "auto-sum" column formula all the way down for the future days/months. It now shows "0.00" all the way down on future dates that I haven't input #s. Is there a way I can set it to HIDE the "0.00" sums if I don't have anything for it to add in the 1st 2 columns?