Extranet Sharepoint Access Using Windows Authentication

Hello,

I am trying to setup WSS 3.0 for extranet access. We have Franchises and Dealers not on our network that need to get to sharepoint. We do not want to set them up for VPN access. When I go in through the network, I can access Sharepoint just fine. When I go into it from an outside computer I get to the login screen just fine. After I login in, I get "Can not display page." I can only assume that this is because I am using windows authentication and am not on the network. Can anyone please help??? We have Sharepoint set up with an external IP but something is obviously missing.

Mike