Reader Jay has a possible solution if you're having trouble with Netflix streaming on Windows 7 or Vista Media Center.
"I have been noticing HD playback issues when using Media Center in Windows 7 and Vista for Netflix playback. It is more like a shutter or jitter. I narrowed down the issue to GPU Acceleration is not enabled in the Silverlight/Netflix Plugin for WMC. If you do "Ctrl", "Shift", "Left Click"; under A/V; you can see that GPU Acceleration(Attempted/Enabled) True/False, playback has jitter. If you do the same thing in the Browser playback on the same machine GPU Acceleration(Attempted/Enabled) True/True, playback has no jitter. I have checked 5 different machines with windows 7 or Vista and they all have the same issue. I am not sure who to contact for this issues Netflix or Microsoft, but I am sure that no one would listen to me. Maybe if more people complain this will get fixed."