I was using an onboard ethernet card, not sure what model it was, but it worked fine in OSx86.
Then, it unexpectedly died, so I had to replace it with a card from another computer I had lying around the house.
So right now I've been using a PCI ethernet card (it's a Realtek 8139, compatible with OSx86).
OSX recognises the PCI card, but it doesn't seem to work.
I've tried reinstalling OSX thinking that might fix the problem, but no dice.

Any ideas of what I should do?

it seems that there is no drivers for that card ... my suggestion is to by some compatible card..they are not so expensive...

That's what I thought, but on the wiki's HCLPart page, under Realtek, the first one on the list is my exact card:


So it should have drivers, shouldn't it? And it's being recognised, it just doesn't seem to be configuring.