calling all Cisco gurus!

hey ppl, I have two 1604 Cisco routers I want to set up with my cable modem connection.Each only has one e0 port. If I connect the cable to one 1604's e0 port do I need to setup DHCP on int e0 to recognize the modem's ip addy every time it changes? I'm running r11.1 on the 1604 routers.What would be the command for this? Any help is appreciated https://discussions.virtualdr.com/im.../2012/05/1.gif

My layout:
cable modem---->e0/Cisco1604_A/serial------->serial/Cisco1604_B/e0---->Cisco 2900xl switch------>PC

-l8r