Well, if your ethernet device exists (you can check it with ifconfig -a) then the problem is only that there is no IP assigned to the interface (and no default route). If you're okay eth0 will show up in ifconfig -a.
If the problem is in the kernel not able to recognize or successfully set up the driver for the device then I have no idea what to do except try the newest kernel.
Otherwise, try something like this as root, this shows 192.168.0.123 as your IP and 192.168.0.1 as your default gateway, for example.
ifconfig eth0 192.168.0.123 netmask 255.255.255.0 up route add default eth0 route add default gw 192.168.0.1
If that gets you working, my advice ends at sticking that stuff in /etc/rc.local so it happens every boot, but more experienced people may have better suggestions to make it work with the system tools.
- -Andy
I have had the same problem with the nforce based motherboards. The one thing that I tried was to turn off kudzu and it seems to work. I can connect to the internet and the internal network.