FYI:
In case anyone else gets this error, I got six identical error messages in a row when clicking the launcher's Play button. Clicking OK on each of these errors still allowed me to continue on to launch the game, but I wanted to fix the problem. I didn't continue on to play the game without fixing the error so
I don't know what effect not fixing this error has on the rest of the game.
[ The procedure entry point Direct3DCreate9Ex could not be located in the dynamic link library d3d9.dll ]
After digging around on the net for a bit, I found that there is a conflict with the "new" NVidia Geforce Experience.
I am running Win7 x64 with two GTX460's in SLI. Yes, I know they're old as dirt, but they are absolutely stellar cards and do the job quite nicely.
I uninstalled the NVidia GeForce Experience from Programs and Features in my control panel. This removed the icon from my system tray, but the NVidia Control Panel still launched from the start menu and the control panel and still functioned properly. The video drivers still function properly.
The game now launches properly with this SweetFX modification and with no errors.