Your initial problem may have been related to project dependencies. I unloaded the irrlichtsmartbody project sine not everyone would want to tie SmartBody to irrlict, but doing so kills the dependencies on the other projects. So, as you figured out, you need to build SmartBody first.
The lastest SmartBody sdk is set up to use irrlicht 1.8.1, not 1.8.
So the C++ header settings (Propertes->Configuration->C/C++->General) should have a reference to ..\irrlicht-1.8.1\include, and the linker settings (Properties->Configuration->Linker->General) should have a reference to ..\irrlicht-1.8.1\lib\Win32-visualstudio
If your Visual Studio automatically brings in irrlicht-1.8, is there some kind of global header directory that points to the older irrlicht versions on your computer that is automatically added to the project headers?