I don't know if you added a portalalias in your DNN install or not but you're going to need one. I also don't know how much you know about IIS/Networking/etc so bear with me if you know all this already. When you install DNN for the first time it creates a portalalias that just points to localhost (your computer). However if you try to use that URL from another computer (http://localhost/dnn47) it's just going to try to look for that site on that computer not yours. What you need to do is add a portal alias (under Admin->Site Settings) that points to your computername/dnn47 or to your IPAddress/dnn47. Then it should work unless your network is setup like the network is where I work which blocks traffic on port 80 between our computers.