kincorransw, Cointreau IS a brand name of orange-flavored liqueur; however, it is a distinct alcohol unto itself apart from triple sec. Cointreau is brandy-based, while triple sec is not. Cointreau is considered by many to be "top shelf" and will not normally be found in the "rail" at a bar, while some brand of triple sec invariably will be there (i.e., for Long Island Iced Teas and other drinks that do not require high-quality ingredients).
That being said, I'd love to try this recipe some day (when I have the $$$ to buy a bottle of Cointreau, instead of having to just look at/use one at the bar where I work)!!!