Have a look in the Device manager, under "Network Adapters, and see if it is listed there. You may be able to disable it.
Also open MsConfig - startup Tab, and see if it is starting automatically with windows 7.If it is, untick it.
Either of these, if present, will stop the message, but, fwiw, you did not need to be on the internet to install Windows 7,. It is only advised, for the purposes of updates to the install. At the moment there are none such.