Това решение предоставя операция CONVERT_IMPLICIT за вашето условие в предикат
SELECT *
FROM xxx
WHERE CAST(dates AS date) BETWEEN '1/1/2013' and '1/2/2013'
ИЛИ
SELECT *
FROM xxx
WHERE CONVERT(date, dates, 101) BETWEEN '1/1/2013' and '1/2/2013'
Демо на SQLFiddle