If you look on the existing PC, there should be a hidden directory in your user folder called .networkassistant (viewable by going into Windows Explorer menu and choosing Organize > Folder and Search Options > View > Advanced Settings and click the radio button to "show hidden files folders and drives").
That folder has a subfolder called "communities". It contains a set of XML files with the community info in them. You can copy that over to the new machine.
I'm not positive if the password folder can be copied over similarly.
