How can I give VPN clients a gateway address if the win2k8 server is not the DHCP server?

I have a Windows 2008 server box that runs in a very simple network.  There is no domain, just a workgroup, and the DHCP is being provided by the router on the network.  We setup a simple routing and remote access "custom configuration using one nic" since there is only one nic on the server.  I am able to successfully connect to the VPN server from the outside world, but I really can't do anything.  It assigns me an IP address from the DHCP server so I assume the win2k8 box is doing what I wanted and it's relaying the DHCP off to the router . . . but when I check what I get assigned as a client, I get an IP address and a subnet mask, but no gateway.  I assume the lack of the gateway is the reason I can't browser any network resources and the internet on the client machine does not work while I'm connected to the VPN?

How can I get around the gateway issue or whatever is causing the VPN clients to now have access to file shares or internet access (even threw their own internet) while connected to the VPN.

Thanks!