Sometimes you need to edit the ini file(s) of games so the screenshot function will work, although I do not believe this was the case with Kot0R or Kot0R II. More likely, you either, while running vista, installed it into the Program Files -thus making it more difficult to edit, even by the game itself, or you need to hit "Prnt Scrn" and then open a program like Paint or Photoshop and past the captured image onto a blank canvas.