Excel 2007 : Circular Reference Issue

I have attached an example of what i am trying to do exactly. In cell A5 you will see the formula.

I want to be able to refer to cell J5 and if there isn't an "x" than add 1 to the previous used cell in column B and than move the number that will be populate in A5 to B5. However i create this circular reference because it keeps searching for the last used cell in the column B. I will like to apply this formula to all cells in column A and referring to the corresponding cells in column J. Does anyone have any idea on how to overcome this problem