Hi Sandy,

This is not a conditional formatting issue.  You could consider an
Worksheet_Change macro.  Something like this:

Private Sub Worksheet_Change(ByVal Target As Range)
   If Target = "" Then
       Target.Interior.ColorIndex = 6
   Else
       Target.Font.ColorIndex = 3
   End If
End Sub

However, this will format the cell if the user changes something and then
changes it back to the original value, for example they use undo.

Also, as written this works with every cell in the worksheet.  If you want
to control which cell you need to define the range by adding something like

Private Sub Worksheet_Change(ByVal Target As Range)
   Set isect = Application.Intersect(Target, [MyRange])
   If Not isect Is Nothing Then
   If Target = "" Then
       Target.Interior.ColorIndex = 6
   Else
       Target.Font.ColorIndex = 3
   End If
   End If
End Sub

This code needs to be added to the Sheet module of any sheets where you want
it to work.  Note that MyRange is a range name you have defined in the
spreadsheet.

You can compare two workbooks for changes using one of the VBA add-ins you
can find on the Web - Google "Compare workbooks" and skip the ones that use
Excel's built in command Windows, Compare...

Cheers,
Shane Devenshire
Microsoft Excel MVP