Is this on your local computer? If so then go to the IIS admin console
through the control panel | administrative tools | IIS admin. Right-click on
the default web site node and set the port number there.
If you're on a broadband connection though you may need to be on another
port as some broadband software blocks port 80 to prevent you from running a
web server from home as a possible business and to prevent some viruses from
jumping around.
If you're using VS.Net 2005, make sure that you aren't opening the the
built-in test server instead. This won't have anything to do with IIS and
dynamically assigns ports on it's own.
