A long time ago I discovered that analog VGA cables degraded the signal if they were too long.
Everything was fine until the cable got longer than about a meter.
This was the case when using one monitor with 2 computers and the signal needed to go through a switch box.
I remember going out of my way to buy expensive, but good quality VGA cables just to get a decent video signal if I wanted my computer to be some distance from my work area.
My experience is that all of the slight shadowing that comes with VGA cables went away when I started using a flat panel _and_ DVI cables.
If I need a couple of meters distance between the computer and the monitor I now only use DVI. This is the case when using a video switch box. The cost of DVI cables have come down toward the price of a good quality analog cable, so everything works out fine now.
The disadvantage to all of this is that DVI switch boxes are expensive! Such is life, to be able to see pretty pictures.
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