Microsoft Visual C++ 2010 Express. It is free and very easy to use.
Hint: The linker does not use directly the DLL. It uses files with .lib(MSVC) or .a/so(GCC/Mingw) extensions. After that the final executable needs the DLL that is located in your system32 folder and you should not worry for that because this folder is in the PATH variable on Windows and the application will load the DLL without issues.
So after you download and compile the stuff on MSVC the file name that you must put in the linker is ws2_32.lib.
EDIT: From what I saw, the tossbot have MSVC project files already created. After you install the IDE you will be able to directly open them.