Images as a result of formula

[Bridg389]

Hi,
I want to be able to add a green circle (showing active) or red circle (not active) in an Excel 2007 cell, based on the result of the formula. But I want the text (in my case they are numbers 1, 2,3.. which represent port number) in the cell remain intact. This is the picture of a switch board. It shows which port is connected to what device. If I add a note to the comment box in that cell, showing this port now is connected to someting it will automatically add a green circle next to it, if not it will remain red. I tried using word count (because if I add text the value of the text increases showing now I have someting connected, therefore change the color to green, but I am not good with formulas or VBA at all. Please help.