Shoutbox

How long is your VGA cable? Is it a double shielded cable? Do you use a switchbox to switch between screens? Always use as short as possible doubled shielded cables and try to avoid switchboxes.

Are there any speakers in the neighbourhood (or near your cables)?

And do you use a (anologue) vga cable or a (digital) DVI cable? (I assume it is anologue).

Also note that the screen resolution displayed in Windows is not always the exact screen resolution which is outputted! Some graphic cards allow you to set your own screen resolutions so you can later pick them in the list. Thus, although they are in the list, it doesn't mean they are always supported. Some video cards also alway you to use non-supported resolutions by using interpolation (this is again not seen in the default Windows dialogs, you need to look in the advanced settings of your graphics card for this).

Note that some LCD panels also allow you to shift the image left or right. The same with the video card driver. Make sure both are set by default (middle) and not one completely to the left and the other completely to the right as that might also distort the image (giving ghosting).