"problem hooking up router to home network"

I recently got a linksys cable/dsl 4 port router, I am tring to hookup 2 cpu's to my motorola surfboard cable modem. Both cpu's have worked straight from the c/m. I turned everything off, waited about 30 minutes, turned on modem first as soon as modem had good link indication I turned on router and plugged the c/m into the router and hit the reset on router and waited for awhile, they handshaked, plugged cpu into router and waited, cpu's are setup for automatic dhcp addressing, as is the router, but no joy. I dont have permision by isp (comcast) as my bill is already 100 a month. I dont want to buy another ip when they will just subnet mask the ip address anyway. will I have to configure the router to clone mac addresses. maybe I missed a simple step somewhere. Any help ?

Is your router getting an IP address from your cable modem? If not then it is a config problem with your router. Try changing the settings or upgrading the firmware.

If the router IS getting an ip address then you set up something wrong with your computer config.

Mike