How do I allow or disallow editing

I have a form (in MS Access 2007)that is used an an input form for
updating linked tables.
I want to change the property of some text boxes on the form to be
editable based on the contents of another field.
For example; if a field contains a date (delivery date)in it, I want to
no longer allow the user to change the EquipmentName or
EquipmentQuantity fields. I want the the field to still be displayed
but no longer capable of being edited.
Is there an easy way to do this?
I prefer to do this without writing VB code, but I can if that is the
best way.
Thanks!