With the computer hardwired to the router, please check the IP through the command prompt. By the way, were you able to do follow the steps for the LAN to WAN method in the link that I gave you? The router should keep the IP address that you have assigned to it and you should be able to access the setup page of the router through that. If not, you may need to update the firmware of your router. You may get the file from this link, http://support.linksys.com/en-us/support/routers/E1200
To do the update, please refer to this link for the steps, http://kb.linksys.com/Linksys/ukp.aspx?vw=1&docid=e9c2361ee7974d75913e61386a712188_4030.xml&pid=80&respid=0&snid=2&dispid=0&cpage=search
Hope that helps.