I am on a project that requires the use of C# and C++, is it possible to compile both languages in the same compiler without spending $200 on the full version. When I try to add a .cpp file to C# it says 'Make sure you have installed (.cpp) files.' Does anyone know how to do that?

Create project from type VC++ and add its output assembly to C# project. I'm using VSTS 2008 which permits that, I don't know what version you're talking about.