Microsoft Visual C++ 6.0 is no longer available from Microsoft. However, for backwards compatibility, a version of SICStus is still available that uses that C compiler and its corresponding C librarues.
Visual C++ 2010 SP1, is the latest C compiler from Microsoft. A separate version of SICStus Prolog 3 is built for use with this C compiler. Applications built with this C compiler, e.g. SICStus Prolog runtime systems, requires that the corresponding C libraries have been installed. If you distribute runtime systems to machines where SICStus Prolog is not installed then you need to ensure that the C libraries are installed by your installer, e.g. using the Microsoft Visual C++ 2010 SP1 Redistributable Package (x86).
It may also be possible to use Visual C++ 2010 Express, availale for free from Microsoft, but this has not been tested.