What's the picture in Device Manager -- yellow flagged, resource conflicts ? Have you updated the driver from the motherboard maker's site or from Realtek ?
Worst comes to worst, buy a PCI network adapter for peanuts that comes with a driver disc -- then either disable the Realtek or let them coexist..
Its not flagged and it is updated by windows 7 if I recall. I went to my Mobo manufacturers site and downloaded the only thing i could find for my Ethernet NIC.
I will look for exact drivers for it in the meantime, thing is I never did it in the first place...