If your monitor doesn't support 1:1 pixel mapping, see if you can set it in the driver of your video card ("GPU scaling" or something)... although in this instance you may be SOL.
I'm looking to buy a small netbook (a laptop is too bulky for what I'm doing) where about 99% of what I'm planning to run will be fullscreen programs running in a 4x3 aspect ratio. All netbooks I've ...