OK, I couldn't wait. I work from home so I had the ability to test this right away.
I've installed a Trendnet Gig-E NIC, which uses the Realtek chipset. As stated earlier, BBC America seems to be the worst offender when it comes to pixellation. I just watched 10 minutes of BBC-A and did not see a single pixellation event. Also noticed no audio dropouts or stutters. I'll keep an eye on it and report back.
I am disappointed that this points to Intel being the problem. I would prefer to see Intel fix the problem, I don't want additional heat generating cards in my HTPC.