Advanced Conditional formatting

Hello all,

I'm trying to make a spreadsheet, were i have a Date Due, and a Date complete Column. I have conditional formatting on the date due, to change the colour of the cell as the date gets closer to the real date.
However i would like the spreadsheet to be able to colour the cell green, when a date has been entered into the Date complete, it does'nt matter what date, i just want to stop the red in the date due column when the Task has been completed.

Kindest Regards

Alastair

Here is the sheet in progress
\1
What im trying to do, is make a cell in date due, turn green if there is a date in the Date complete cell next to it!!!

Hope this helps Kindest Regards.