Conditional Formatting Question

Hello,

I am having problems with conditional formatting on Microsoft Excel 2003. The Excel file I am trying to format is basically a long list of tasks that I need to do in work and then 2 columns; 1 with date due and 1 with date to start. I want to highlight any dates that are before today's date red, any with todays date orange and any date after today's date green. I'd like any blank cells to also remain blank. Can anyone help with this please, I've tried a few formulas after reading up on a few forums but I'm still having problems.

Thanks in advance,

Craig