Anyway, the 1394 realtek 8801 would seem to be your FireWire controller, and not relevant to your Internet connection (please correct me if you have some kind of FireWire modem or something).
Anyway, having looked at the Shuttle product page, and the manual, there is no indication that this system is Linux compatible, and nForce 2 boards are still rather touchy, but this thread elsewhere on these forums
indicates the solution. I would suggest going to the nVidia site and looking for the kernel modules for your nForce 2 mobo's NIC. Don't forget to read the readme first.
Hope this helps.