Need help setting up a router with Comcast cable

So, I have this Netgear CG814WG router (version one as far as I know) and I've been noticing that everytime I forward a port everybody else that is trying to stay online gets kicked off after about an hour or so. This, of course, makes them angry with me and I have to disable my forwarded port. I cannot make a static Ip address because the DHCP range is 192.168.0.1 to 192.168.0.254 which is every Ip address that is possible. With the POS Comcast firmware it doesn't allow to change much. Just security. I cannot login with the "superuser" account either. I have tried setting up my linksys Wrt300N router straight to the Comcast cable modem but to no avail. I cloned the MAC address of the Netgear. I put in all the Internet info. And I tried to use DHCP to get an IP from Comcast I cannot think of anything else that needs to be done. Btw, the Netgear router is hooked up using a coaxial cable while I was trying to hookup the Linksys router with ethernet.

Any suggestions? I really want to hookup the Linksys router with Comcast.