I recently got cable internet, and have 3 computers to get online. I got a Netgear router in order to have everything connected, and that worked fine.

However after getting annoyed by having to mess with port forwarding and things not working half the time, I decided to change the set up.

The plan was to hook this computer up to the cable modem, then run a crossover cable from my secondary NIC, to the routers internet port, then plug the other computers into the router. I did all that, and turned on Internet Connection Sharing for the primary NIC... No luck. The computers behind the router cannot access the internet. The IP's seem to be right, it should all be working, in theory...

I really have no networking knowledge or experience, so I really don't know what to do. :-\

The easiest way is to ditch the router and use a simple 4 port HUB instead.

Internet Connection to first PC

First PC setup ICS, which installs a basic DHCP server.

RJ45 Patch Cable from each of the PC's to the HUB.

On your other two PC's set the TCP/IP to "assign automatically"

You only need the TCP/IP protocol:

http://www.wown.com/

Is it impossible to do with a router? Or do I just need to configure the router a certain way or something? Getting a hub is a little out of my budget(read: none =P) right now.

Try plugging the computer doing ICS into a LAN port on the router, rather than the WAN port.

ICS generates IP Addresses in the range 192.168.x.x; this range is by definition "local" and the DHCP server inside routers defaults to ignoring any packets from this range they "see" through the WAN port. It's the basis of NAT (Network Address Translation) Firewall security.

Go into the router setup, disable DHCP, and it's a switch (hub). Then ICS feeds the other clients, using the router just as a switch for packet forwarding. I'm not sure why you'd want to do this because then your host PC has to be on for the rest of your LAN to talk to the Internet. Also you still have to install a software firewall on your host PC or your LAN will get hacked. You'll still have the port-forwarding hassle.

Sounds like the problem you're really having is with your router's firewall. NAT routers aren't real good for online gaming; some of the newer ones use SPI packet filtering which is better at this. Netgear routers used to have a very good reputation for quality and reliability but they got bought out awhile back and rumor has it that their standards have slipped. You might check out another router, see if that works better for what you want.