After all the things I tried to fix, the answer was so obvious and I didn't even think of it...
I just needed to reinstall/update my video drivers.
In my rush to get this game running, I forgot that a complete reformat would leave my operating system completely driverless.
Many thanks, killerinsidee.
Side note to ultimecea, Direct3D is a part of the DirectX package, and is included with (among many other versions of DirectX) DirectX9.0c.
DirectX9.0c is also the most current DirectX that can be run on systems preceding Vista (meaning XP or Windows 2000). In addition, the official system