I'm running a 32-bit Vista and I've tried:
-Running as administrator
-Setting compatibility to Windows XP (serv pack 2)
-Setting Regional Language to Japanese and English (US)
-Running Ren'Py 6.9.2 (works)
-Added DEP exception for Katawa Shoujo
I'm currently running 1680x1050 display with 32bit. I have 3G Ram and running GeForce 8800 atm.
Here's a picture of what happens whenever I open the game.

I might not have posted something that I've tried. Any help is very much appreciated. I've heard only very good things about this Visual Novel and I'm yearning to have a go at it.