I am using MSPaint (Windows Vista version) mainly for line drawing pixel art. When I save and reopen dithering messes with my nice crisp lines. Am I correct in thinking that if I use a palette of only the 256 windows colors it will prevent this? I have looked extensively, but nowhere can I find the color codes to do this. I am confident converting between hex and RgB codes, I just need a definitive list to work from.
In my opinion the way to solve the dithering is not saving in a 256 file format at all.
Try saving in png or tiff if you can, or in bmp but 24 bits. This way you will save in the file the same image as you worked it, with no transformations.
But If you want to try the specific colour palete, I extracted this from a file I created on the version installed on my computer.