Hey Drew -
These files were pulled out of the Measurement Studio support for Visual Studio 6 in 8.1.2. Previous versions of Measurement Studio support for Visual Studio 6 should install these files. However, these files are for specific instrument drivers - the one you refer to is an American Reliance Power Supply. So - unless you are trying specifically to interact with one of those instruments, you should just be able to remove references to NiArppsComponent.h and any others that give you trouble.
Let me know if this does not solve things for you.
NickB
National Instruments
