Im not expext, but lots of people around me, spoke so this is fake, you can have few DX10 like effects, but DX10 driver is highly integrate to Vista, which can restart parts of GPU and texture windows by Aero with small performace usage, this isnt in present XP architure possible. But i think so i possile make by way DX9, DX10 like effects, with slower GPU acceleration or a bit worse graphics quality. Problem isnt impossiblity of paint these effects on screen, but in speed of acceleration.
Make DX10 incompatible with XP, is next of MS big mistake, bad they have money and old aplication as surety, so they can everythigh.
But tomorrow i saw some brutality, DosBox in emulated XP in Linux on PS3:
http://www.youtube.com/watch?v=Vz9UtiTqaoI&eurl=http://bonusweb.idnes.cz/pc/zurnal/Section.idn Artificial imcompatibility todays platforms is bad for players. We can have universal Linux OS for all platforms or universal Java application, if leaders of company learn common sens.