I've got a problem with the demo also. After I installed it, I tried to run it. But then it showed the message:
"This application has failed to start because d3dx9_27.dll was not found. Re-installing the application may fix this problem."
I did as it told me, but the same thing keeps popping up every time I try to run it.
By the way, I downloaded it from Game Spot. Should I try another source?