thanks for posting such a useful information.
actually, i am making same project. since now, i am able to access my ethernet shield from web browser of same network but i am still a newbie in field of networking and i dont know how to route the traffic to arduino through a router. i m using a router after a modem which further signals my arduino and laptop. so, can u tell in steps, what is procedure to operate ethernet shield from different network. i am using dynamic dns service. i m waiting eagerly for your response. this is veryyyyyy important for me. plzzzzzzzzzzzzzzzzzzzzzz help me.