where are you typing the url? on the win2k3 machine?
also have you checked that it is running as an asp.net app? Does it have an application pool on the IIS page? have you allowed asp.net to run under iis on the win2k3 machine?
Are there any other asp.net apps running on this server?
If you dont understand how to setup a Win2k3 machine for IIS and ASP.net let me know and i will give you the steps to take. It is quite simple