It should work with everything set to DHCP.
Plug the Vonage WAN port into a LAN port on the Linksys.
Turn it on. It should get an IP from the Linksys and should start looking for the Vonage Server and set itself up
My setup even has a Linksys switch between the Linksys Router, so I didn't have to get tricky getting the computer in the other room (where the Vonage is) to keep working with the LAN (2 computers, router, and cable modem in another room).