Excel 2007 : Mutiple conditional formatting based on a drop down menu

Hi there,

I am no expert in Excel and there must be a really simple solution to my problem.

Basically, I have a drop down menu with 2 options. Depending on which option is selected I need a set of conditional formatting rules to apply to a separate cell.
So in this separate cell I will have a numerical value which needs to be assigned a colour based not only on its numerical value but also which option is selected in the drop down menu.

I hope that makes sense