It sounds like your router does not have Dynamic Host Configuration Protocol (DHCP) enabled, but your network connection set to automatically obtain an IP address.
You may try manually setting your IP address to either 192.168.0.2 or 192.168.1.2 (192.168.x.1 is a very common default router address). For a subnet, use 255.255.255.0 (Gives you the last octet for PC assignment).
You may try connecting to the router at 192.168.0.1 or 192.168.1.1, and enable DHCP, so that the router may 'hand out' IP addresses for any machine requesting one.
EDIT:
"By default, your Netopia gateway has an Ethernet IP Address of 192.168.1.254" also, "...[has] DHCP (IP Address Serving) enabled."
This means that you should be able to reset the router to default settings and then just set your network adapters tcp/ip properties to obtain an IP address automatically. The DNS should be set to automatic as well.
If you have trouble trying to connect to the routers configuration page, set your network adapters IP to 192.168.1.2, subnet 255.255.255.0 then go into a web browser and go to '192.168.1.254'. you should now be looking at the routers configuration page. This should however not be necessary since a successful reset of the router should enable DHCP, and only require you to set your network connection to automatically obtain IP and DNS.
EDIT2:
"And I dont have a modem i think" - YOU
If you don't have a modem, you will not have an internet connection. You may still use the router for a local area network (LAN), but you will need a modem and to subscribe to an Internet service provider (ISP) in order to connect online.
What do you have plugged into the router?
-One power cable.
-One network cable for the PC.
-What else? (you need an internet connection to be plugged in)