There are a few threads here about the HD931 as well. If you have a display with an HDCP-compliant DVI input and if it's a JVC, Hitachi, Samsung or Pioneer Elite, you'll probably be okay. Other brands will usually not display 1080i.
After testing an HD931 on my showroom floor, and being less than pleased with the results, I took one home this weekend to test on my Hitachi 65SWX20B. I remain completely unimpressed by this product. I thought that the 480p and 720p DVI output modes looked markedly worse than my Panasonic RP56 over 480p component video. There was a substantial lack of definition in both sharp foreground and "soft focus" background objects, and the player itself is very slow in disc handling functions. Skipping chapters, navigating menus, changing layers... all are much slower than they should be. The 1080i output of the Samsung was certainly not as bad as the 480p or 720p, but in the very best of conditions it only looked similar to the RP56 in terms of video quality. The DVDs I used for these testing purposes were Fellowship of the Ring, Sleepy Hollow, and O Brother Where Art Thou? My opinions were shared by my wife, who is far from picky when it comes to video quality. She noticed a substantial difference between the RP56 and the HD931 while in 480p and 720p. In 1080i, she said the picture looked exactly the same. I still contend that there was visible posterization in background images. Is it possible that the DVI connection brings out imperfections in the source that component cannot? Certainly. But regardless, the Samsung HD931 lessened my enjoyment of my home theater.