1) Can you run the game at all?
2) I'm assuming that you're using a modern version of Windows (i.e., Vista or 7), so did you install the game according to the large-print instructions at the top of the second post
in this thread
3) TSL supports 1280x768 natively. All you have to do is set the with and height values to 1280 and 768 under BOTH "Display Options" and "Graphics Options" in the swkotor2.ini file.