27th Ottawa Antiquarian Book Fair - Oct 27-28, 2007

They don't seem to have a website, but the Ottawa Congress Centre events site says

The Twenty Seventh Ottawa Antiquarian Book Fair has become an exciting fall event for book lovers from across Canada. A display and sale, recognized as one of the finest book fairs in the country, features rare, unusual and collectible books. The fair will include over 40,000 items, dating from the 15th century to the present day, displayed by over 65 booksellers from across Canada.