If i remember correctly then the Tut's say that no support will be given should you use ms visual c++.
This means that if you experience problems during compilation then the lecturers won't assist assist you
..wrt submitting you code in ms visual c++ .. well that i can't answer and if you ask me it's gamble especially if you say that
you include directives that are not mentioned.
I would suggest that you stick to the GNU compiler only for submitting and continue to use visual c++ for your own experience and pleasure !? .
I got a bit frustrated with the ide for this unit and installed code::blocks (http://www.codeblocks.org/)
Not perfect but it works way better + it includes GCC so no problemo (will even use other installed compilers if it can detect them) when doing assignments.
It's a small install and works out of the box (don't know about vista, but it runs on Windows 2008 so it should be fine ).
I also got frustrated with the IDE plus the debugger doesn't work on Vista. Changed to MS Visual Studio two days later.
If you are using the express edition click "next" during project creation and select "empty project", instead of clicking "finish" after giving the project a name. This won't include the precompiler directive.
To disable the headers in a current project go to Porject->Properties then locate Configuration Properties->C/C++->Precompiled headers and select Not using headers. Now you can get rid of the stdafx directive