All of my video and DirectX drivers are up to date. My guess is that the game uses some fancy graphics stuff that only newer cards support. A lot of games allow you to turn off a bunch of that stuff in options, but FW doesn't.
Here's what the terrain looks like on the first goblin mission:
Also, when you mouse over a unit, everything but the GUI goes completely black.
I'm sure there's nothing to be done. I'm just disappointed I won't be able to play the game.