Welcome Siram. What size is your display? Here is what Oppo has to say:
"
The DV-981HD features video processing with "DCDi by Faroudja" technology and video chipset by Genesis/Faroudja; the DV-970HD and DV-980H use a different chipset technology for video de-interlacing and up-conversion. While all three players produce excellent picture quality and the difference is subtle, the "DCDi by Faroudja" technology is able to handle some tricky video contents. On very large TV or projector screens, the difference could be noticed by experts or videophiles. When benchmarked with contents designed to test video performance, the DV-981HD will score higher than the DV-970HD and DV-980H."
I am using the 980 with a 56" DLP display, so the 980 works best for me. If you have a large LCD display, you might consider the 981. If your display isn't that large, either the 981 or the 980 would be fine.
More comparative information on the Oppo players can be found
here
