You can obtain a copy of MASM 6.15 as part of the Visual Studio Processor Pack. Follow this link: http://msdn.microsoft.com/vstudio/downloads/ppack/download.asp It contains support in VC++ and MASM for Intel's SSE, SSE2 and AMD's 3dNow. There are some issues with recompiling MFC, though after installing the VC++ part of it. (kinda weird).