When I was looking into eSATA, some of the info seem to suggest that eSATA ports must match (no eSATA to SATA), and you must use a certified cable.
The interface seems to be designed for H/W like this:
http://www.bjorn3d.com/read.php?cID=912
Or hopefully something like these...
Strange that we would have such different experiences. Besides the odd color banding around primary colors of overlay graphics (with hardware decoding) I have noticed more saturated colors with less noise, and a sharper image.
Do you have hardware encoding enabled?
No I use two DirecTV satellite boxes connected to the two tuners of the Nvidia DualTV via S-Video cables (the Hauppauge cards were connected the same way).
The problem I had with my Hauppauge cards was that if I enabled 'Hardware Encoding' in the DVD decoder software (which takes a big load off the CPU and hands it over to the video card-which is good if you have a high-quality DX9 card), there would be strange banding around primary colors...
The Nvidia card is 'designed' for MCE, but comes with standard WDM drivers, and can work in single or dual-tuner mode in any Windows S/W. Do some research, all this info is available via the manual and reviews.
I had two Hauppauge 150's (like a single 500-same tuner), and the Nvidia DualTV I replaced them with has a MUCH better picture. The old NVTV card wasn't that good, but the new one is great. When checking reviews make sure you're seeing the NEW one.