Name it Plugin_VideoDX9.dll (not necessary, though. delete the one already in there if you have to).
There should be 2 option, right? Dolphin OpenGL and Dolphin Direct3D9.
Have you installed VC++ 2008 SP1 and DirectX 9.0c November 2008 at least?
http://forums.dolphin-emu.org/thread-4.html
But don't get your hope up, since DirectX plugin is still underdevelopment.
it would be best if you can upgrade your graphic card, or just stick with it until Dolphin team released new DirectX plugin.
Try to download Dolphin SVN again, older a little is okay, since it is weird there is no Direct3D9 in the graphic plugin.
It might be next week, next month, next year, or maybe it will never be made lol
That will depends on the devs.
There should be a lot, but not in satisfied term...
What the?
http://www.dolphin-emu.com/downloads.php
Tell me what Dolphin you are running. (run the Dolphin and see the upper left of the window, there should be Dolphin SVN rXXXX, if there is).
May I ask your pc spec and what OS you are using.