I have the EXACT same problem. I have found the driver for it, the problem with me is that I cannot enable my Built-In LAN and get into windows to install the drivers. When I enable my Built-In LAN, my computer tries to use it and ends up going into an endless circular loop of failed attempts to use the uninstalled hardware.
Use the Intel Pro/1000 MT Desktop included in Sun VirtualBox. Set the Network Adapter on Bridged Adaptor. Don't set it on Host-Only Adapter. Worked for me. Nevertheless, Win7 also used Windows update to install Realtek 8168/8111 when in Windows 7 host mode. Hope it helps!