I have a free standing set of files not affiliated with any C# project at all that reside in a complicated nested directory structure.
I want to add them in that for
In Windows 7 you could do the following:
Right click on your project and select "Add->Existing Item". In the dialog which appears, browse to the root of the directory you want to add. In the upper right corner you have a search box. Type *.cs or *.cpp, whatever the type of files you want to add. After the search finishes, select all files, click Add and wait for a while...