Conditional Formatting on Date cells

I have attached an excel spreadsheet containing "Due Date" column having date in dd/mm/yy format.

Now what I would like to achieve is that whenever this excel file is open the cells containing date values get highlighted with font color "red" if the difference between the today's date (when the file is opened) and the due date is less than 7 days.

For example, suppose today is 6th November 2008. Therefore the cells A2,A3,A9 and A10 should be in "red" color.

I think I can do this with conditional formatting but I am having trouble putting in the formula.

Thanks.