I would like to thank all of you for your responses.
I want to try that SSE thing. My CPU is an AMD Athlon xp (Barton) 2800+. Supports these: x86, MMX, 3DNow! and SSE. But not SSE2.
These Visual C++ (like 2010) Express editions are very limited. Compiler options aren't accessible. However I have the Visual Studio 2005 Professional, and I found it:
/Property Pages/Configuration Properties/C & C++/Code Generation/
Enable Enhanced Instruction Set = [not set | SSE | SSE 2]
But i think mangos doesn't support C++ 8.0 anymore (i can't find mangosdvc80.sln). So must I get a Visual Studio 2010 Professional edition to compile mangos project?