If it does not stay at the same setting you can go into the options for the game and set the resolution to what you want that should be no problem. So you could have 1080p at the desktop and play the game at a different resolution with no problem. Depending on what your new monitor supports it may not be exactly 1024x768 but you can get close like 720p it just depends on what the monitor allows.
Thanks man. I am also upgrading my processor too!