I'm having the same problem. I'm using SVN 3300 x86 and I can't get Simplepad to appear in the plugin list. The list is empty.
I did try some things... I installed the above DirectX November 2008 updater and the MS Visual C++ Runtime 2008 SP1 package. Apparently I already had the runtime installed because it gave me an option to repair files. I repaired anyway to make sure everything was installed correctly. These are the only 2 requirements I see in Omega's list of minimum requirements. Every revision seems to have different problems with plugins. But I did notice that after updating DirectX with Microsoft's web updater, the Wiimote plugin appeared, but not the Simplepad plugin.
Edit: I remembered I replaced the controller plugins with plugins from SVN 3404 to make sure they weren't corrupted. Apparently this is why Simplepad wasn't showing up for me. Problem solved!
I did try some things... I installed the above DirectX November 2008 updater and the MS Visual C++ Runtime 2008 SP1 package. Apparently I already had the runtime installed because it gave me an option to repair files. I repaired anyway to make sure everything was installed correctly. These are the only 2 requirements I see in Omega's list of minimum requirements. Every revision seems to have different problems with plugins. But I did notice that after updating DirectX with Microsoft's web updater, the Wiimote plugin appeared, but not the Simplepad plugin.
Edit: I remembered I replaced the controller plugins with plugins from SVN 3404 to make sure they weren't corrupted. Apparently this is why Simplepad wasn't showing up for me. Problem solved!