It was for me as well. I had to play around with the video drivers and the audio drivers for about 3 weeks. I installed the cyberlink dvd that came with the TwinHan this past weekend and the sound finally came in great. It was previously too low or only came out of 2 speakers (I have 5.1 sound).
Also, I was having trouble with the picture studdering quite a bit. Then I downloaded the "Pure Video" Driver from NIVDIA website and presto!, no more studdering. Unfortunatley, it is a 30 day trial version. I have to purchase the driver. But, I would be willing to spend the money if it fixes the problem. PBS-HD rocks on this system!
The only small thing I've noticed (I am so picky it's not funny
) there is a faint ban that goes across the middle of the TV. This ONLY happens when using Mytheatre. This only evident when there is an absence of video or very dark scenes. But, with the problems that I had with ProgDVB, this is very negligible in comparison.
Hope this helps.