DIR-655 acting as cable modem?

I recently moved to a new home and had to change my ISP. My old ISP provided a cable modem, that connected to my DIR-655 and worked flawlessly. I could setup port forwarding to connect remotely to all my servers or computers. All my consoles worked great with open NAT.

Now with my new ISP, which is also cable, they told me a cable modem was not required. In fact the fiber runs to a box on the side of my house, and from there cat5 into the house, which is plugged into my DIR-655. The DIR-655 is assigned my public IP. Since I've had it configured this way, I CANNOT ping my public IP, nor can I connect via my remote connections anymore (VNC especially). Also my consoles connections are not working properly because the NAT isn't opened.

I'm guessing that the DIR-655 is acting as the cable modem in a sense, and it's not designed to, so I need to put something in front of it. Should I buy a cable modem and configure it so its INTERNET -> CABLE MODEM -> DIR-655 -> INTERNAL NETWORK? I also heard I could get a router and configure it in bridge mode. I'm really not sure how this would work though, I've always had cable modems. Reading this thread gave me the idea to put a router in bridge mode, the guy took a 2wire wireless and configured it for bridge mode and it seemed to work: http://social.microsoft.com/Forums [...] 57caf1374/

What would be the best way to fix this and get my DIR-655 working normally again? Do I do what he did and get a router in bridge mode? If so which is the best one I can go pick up at best buy in my area, or do I have to find the 2wire he used?

Thanks!