Conditional Formatting

[clylab]

I already have conditional formatting in a cell so that if the cell value is less than a certain number the cell appears RED. The cell containa formula which is linked to other cells. I also want to add another condition which makes the cell appear a different colour should the value in another cell be greater than 0. For example: Cell A1 contains a formula and the conditional formatting means if the value is less than 100 the cell goes RED. If cell B1 contains a figure greater than 0 I want cell A1 to be a different colout, irrespective of it value, I want the 2nd condition ot take priority. How can I do this?