I'm currently using Intel 82576 Gigabit NICs integrated onto my mobo. Unfortunately, Open vSwitch seems to have driver issues with Intel NICs - they suggested I stop using the Intel NICs and get a Broadcom PCIe card instead, which made me suspicious to say the least.
I think I'm going to go back and tell them their software is an utter piece of crap.
Broadcom NIC's work just fine under Windows 7/8/8.1/2008/2008 R2/2012. If you don't know how to install a driver, then something's up. I have a NetXtreme installed in my file server and it has pretty good performance for an older server grade NIC. Intel's NIC (3COM rubbish) drivers has been hit and miss over the years, so I generally don't use them.