=If (forumla) = colour fill cell

Hey...... first post here.

Let me start by saying how much I have learnt already whilst simply looking for a solution to my own problem!!!!

Okay.... here's where I'm at.

I have two dates lets call them cells A1 and A2. I then have another cell that caluclates the difference in these dates into a simple number (ie not another date) - A3.

I need one of two things.

Ideally I want the whole cell (A3) to appear as a Green (fill) cell if the value is below 5, appear Orange if beween 6 and 9 and appear as red if its 10 or over.

I do not know if you can colour a cell that has a formula in already. So what follows is my current 'work around', which, if you can not colour the A3 cell, then I would need this cell coloured (A4).

=IF(D12>7,"Urgent Attention",IF(D12<5,"New",""))

Please ignore the values in the above formula as I was just testing things out.

thanks in advance.

Lee