Visual Studio 2005 Standard中的OpenMP

I have used OpenMP with gcc for writing parallel code. I am now using Visual C++ 2005 and am trying to figure out how to use OpenMP. There is a compiler option in the Properties->C/C++/Language menu but then it complains the library is missing. Is there a 3rd party implementation for OpenMP or am i just configuring Visual C++ incorrectly?I have used OpenMP with gcc for writing paralle