I believe your router should be your default gateway. I'm assuming that what you're using as a default gateway must live on a different subnet from your machines, thus unless you have the router as the default gateway, your machine can't see any other subnets.
It is even simpler than that. I have a single router and only one subnet. Per your hint I used my router's IP address (192.168.0.1) for the default gateway and nameserver and I am connected. What confused me was the external IP address (69.nn.nn.nn, I forgot it already) that came up in my Netgear router configuration. This is Comcast's (my broadband provider) gateway. But, as noted, I am now connected. Thanks.