I just mean what distro you had installed and what options did you choose regarding the network?
Like I said my board has similar Realtek card on a nForce 630i chipset and is detected by the vanilla driver, if yours is not detected and you didnt install any other network driver, you should consider looking for an alternative/patched nvenet.kext.
If the card is detected but your problem is getting a network connection working on it, sorry but I cant be of much help there as I dont have any wired network connected to my nForce ethernet.