There is more to this issue though. I get the exact same thing. Q6600, 8800GTS 1GB, 4GB RAM, Vista 64.
It tells me the exact same message and i know i have up to date drivers and i have DX 10.
The game still asks for DX 9c, and even after installing it, it still does not recognize it.
JJBuck2, are you also on Vista 64?
Maybe this is a 64Bit issue or a Vista Issue, the game runs fine on my XP 32 machine........