IIS 5.0 request handling issue.

I have a strange problem. In SQL SERVER 2000 when a stored procedure having a statement "WAITFOR DELAY 00:00:05" is called by multiple users simultaneously,then each request is executed as a separate thread and all of them get the result almost simultaneously. But when the same stored procedure is called by an ASP page through IIS by say 10 users simultaneously then each request is queued and they are served in the order First Come First Serve . IIS 5.0 is supposed to be multithreaded and each request is supposed to be handled by a separate thread. But i want to know why each request is queued and not executed simulataneously