Date Insert?

I might be confused, but the Date and Time displays for Notes are toggled by going to Tools>Options pick the Other tab and then Advanced Options.
You can put a check mark next to "When viewing Notes. show time and date."
Please let us know if you're trying to insert the date elswhere. I don't think there's a way, in other locations, to insert a date other than to type it in

Create a Word document just with the date - tick automatic update - in the form you need it.
Then you can insert this document into the notes section of the contact form: open the contact go to the notes section and use
insert/object/create from file

In a new form, select the tools menu | forms | design this form...
Then from the view menu | view code

In the code window, enter the following code. When finished, open the control toolbox and drag a command button to the form. Rename it by right clicking on it and selecting Properties. In the caption field, type in the desired name.

Sub StampDate()
Item.Body = Now() & vbCrLf & vbCrLf & Item.Body
End Sub

Sub CommandButton1_Click()
Call StampDate()
End Sub

You can visit www.slipstick.com for some good add-ins and utilities to do all sorts of things with outlook. Its one of the best sites out there. You can also download a contact template for outlook that already has the code for the date stamp included at http://www.poremsky.com/DateStamp.htm