http://<IIServer>/nwind?sql=SELECT FirstName, LastName FROM Employees FOR XML AUTO&root=root
Is that a typo, or are you trying to pass a variable to a directory? when you say /nwind?sql='foo' then you should get page cannot be displayed, right? Don't you have to say /nwind/default.asp?sql='foo' ??
or will the virtual directory/IIS understand what you mean?