ryu:
If you've connected the router via LAN cable, then you don't need to have any software installed on your computer, except for SNMP (Simple Network Management Protocol) software if you want to monitor your router
Also, if you simply run 'ipconfig' it would immediately close the window. You have to open Command Prompt and then type in 'ipconfig' + <Enter> to be able to view the ipconfig info.
If your PC's IP address is not in the 192.168.1.x range, then you'll need to change it.
Your IP address should be like 192.168.1.100, subnet mask = 255.255.255.0, gateway = 192.168.1.1, dns = 192.168.1.1
I would also advise you to do what Venomous said, by going into the BIOS and disabling the onboard LAN.
I've seen strange stuff with onboard LAN devices when I was working at Stellenbosch University's Student IT Centre... The strangest case I had was that the onboard LAN device simply disappeared from Windows, so I installed an add-on card and then suddenly the onboard LAN device worked again. After I removed the add-on card again, the onboard LAN was still working 100%. LOL.