I've been using an AOC 19" wide LCD for more than 2 years now, I think. All this time, I've just connected it to my PC via the usual analog VGA ports and cable. But as of late, the display has been bothering me as there appears "smudges" on screen particular to the right of areas where there are dark/black pixels. Its like when you write on a piece of paper with a black pen, then while the ink is still wet, you brush your hand on the surface towards the right causing the ink to spread.
This reminded me of my recent experience of moving from analog component video to HDMI on my home tv system. Orly commented that the HDMI system will certainly look better since its digital. So I scrounged around for the DVI cable that came with my LCD monitor and plugged it to the DVI port of my video card, as opposed to, the analog. Since DVI is very similar to HDMI, I reasoned that maybe this should improve my viewing experience.
And what do you know -- the black ghost trail smudges disappeared with the DVI cable. According to Wikipedia, DVI sends color information for a pixel using data. This is unlike analog technology where it is common to have a neighboring pixel affect the color of its adjacent pixels.