You should check in the bios to see if the onboard network adapter is still enabled.
I've disabled and enabled the adpator in the bios with no help.
Its a common problem with the new Intel boards and windows 7.
its either a bios problem, a driver problem or a combination.
Intel have been mum on the matter, but theres MANY threads about this.
Try to contact www.anandtech.com or likewise tech site. They might be able to probe intel into action.