WorkBook open event

[microsoft]

I am having trouble getting my head around the code i need to accomplish
this:
I want it to run when the below event runs.

The logic is:

If there is a DATE(dd/mm/yy) in Sheet2.Column(A) that is => 4 years from
NOW(), AND the value in the SAME ROW in Sheet2.Column C is NOT found in
Sheet3.Column(A) then
the Values in that ROW, Sheet2.Column(C).Value is then placed into
Sheet3.Column(A), AND Sheet2.Column(D).Value is placed into Sheet3.Column(C)

Eg.
Sheet2:

A B C D

12/3/03 Fred 101 Task1 ' Being >= 4yrs
old this data is transfered(copied) onto sheet3.

10/3/05 Jack 125 Task 7


Sheet3:

A B C D

95 ----- Task 4
101 ----- Task 1 ' <====== Due to this in sheet2 being
=> 4yrs old these values are placed into sheet3.



Private Sub Workbook_Open()
' Existing Code below
Application.ScreenUpdating = False
ActiveWindow.DisplayWorkbookTabs = False
ActiveWindow.DisplayGridlines = False
Sheets("NavigationPage").Activate
' Place the current Date on Sheet1 when Opening WorkBook
Sheet6.Range("b1").Value = Format(Now, "DDDD DD MMMM YYYY")
' Place code here to update the data when the WorkBook opens

Application.ScreenUpdating = True
End Sub


Any idea's how i can get this done?


Corey....