Maybe you have to set up your internet connection. Start > Control Panel > Network and Internet Connections > Network Connections > Create New Account (This part can be skipped if you know how to get to network connections faster) And go through the setup and set it up. This is for XP, Dunno if its for 98 or earlier or others. Tell me if it works.
make sure your NIC (network interface card) appears in the device manager. set up the IP and gateway to your router.