Which leads me to the final question...

What's the best way to SELECT - SQL when dealing with memo fields in the WHERE when considering optimization

SELECT * FROM MyTable WHERE !EMPTY(MyMemoField) AND MyMemoField='test'
or
SELECT * FROM MyTable WHERE MyMemoField='test' AND !EMPTY(MyMemoField)
or
SELECT * FROM MyTable WHERE !BLANK(MyMemoField) AND MyMemoField='test'
or
SELECT * FROM MyTable WHERE MyMemoField='test' AND !BLANK(MyMemoField)