It is not proprietary, it works with any source equipment. I bought the 40inch model for a secondary HD set in the basement and the only thing I have noticed is the output resolutions the DVI will work with from the device are 480i, 480p, 1080i, no 720p from the device. Please don't confuse this with the video resolution of the program. For example, my LG4200a QAM box is DVI out at any of the 4 resolutions I listed, but if I set the box to 720p, the TV shows nothing, if I set the resolution on the LG to 1080i or 480p etc, the tv works just fine.
As for DVI-HDMI, I would check Monoprice.com for quality cables at a very good price. I have 2 cables from them (HDMI-DVI)
BTW, I forgot to mention, you can change (at least on the 40inch) what the input's name is, I changed my DishDVI to say Cable and my Comp 1 to say Dish