I have a new build running off an MSI P67A-GD65 mobo and while I'm operating under Windows 7 I cannot get any connectivity to the ethernet port. I bought a Netgear PCIe card which has been fairly plug-and-play.
"What's the problem?" You're wondering.
On another partition I have Snow Leopard running, and under that OS it works perfectly with the onboard LAN but can't connect through the Netgear!
I'd prefer to use the mobo's ethernet port for both OSs and have the PCIe slot free (especially if I can return/sell the Netgear).