Netgear WGR614 and Comcast

I replaced my older "b" wireless Netgear router with a new WGR614 when it began to become very slow when connected wirelessly. After numerous hours attempting to get the new router working I need help! I have followed the Netgear directions and suggestions from different posts here without luck. I have a Comcast cable/phone modem that the router connects to. I know about resetting the Comcast modem etc. I am able to ping the router when it is not connected to Comcast fine. It definitely is a problem with the connection from the WGR614 and the Comcast. The PC works fine when connected directly to Comcast. The older Netgear was up and running in 10 minutes on installation so I don't know what could be wrong unless the WGR614 is DOA. Any suggestions? Should I use a static IP?