takyhon, going to 1280 X 1024 warps the display slightly, as standard computer monitors and consumer TV sets have a 4 X 3 width/height ratio. Try setting your display at 1280 X 960 to get properly "square" pixels.
If this isn't an option in your display properties, get the "Power Strip" utility and make it an option.
In general, if you calculate the number of pixels either 12 X 10 or 12 X 9 gives you, you'll find that a typical 0.25 mm dot-pitch 19" monitor is going to top out at that resolution anyway. Yes, 19" monitors can "display" 16 X 12, and maybe even higher, but they can't clearly resolve individual pixels, so things get fuzzed out.