Default dates in table field properties

I remember this being a particular headache when I took DBI would you mind refreshing my memory?

tblOrder_DateOfOrder field: make the current date the default value for the date the book was ordered

I tried these variations in the validation rule:
Date()
=Date()
>=Date()
No luck :(

I held off on answering this earlier because I thought the demo in class on Tuesday might better display what works. Did it?

If your DateofOrder field is date data type, formatted as long or short date, and you use the function Date(), I cannot see why it shouldn't work.