Maybe, and that is my original question. However, if you run the queries below in SQL Server (version 2000) you get 24 hour difference.
SELECT DATEDIFF(hh,'2006-10-28 15:00:00.000','2006-10-29 15:00:00.000') AS difference
SELECT DATEDIFF(hh,'2007-03-10 15:00:00.000','2007-03-11 15:00:00.000')...