Microsoft has made its x86 assembler available as a free download.  The Microsoft Macro Assembler 8.0 (MASM) is a tool that compiles x86 assembly language programs and generates corresponding binaries. Assembly language programs built with MASM can be edited and debugged using Visual C++ 2005 Express Edition.  The MASM download can be found at http://www.microsoft.com/downloads/details.aspx?FamilyId=7A1C9DA0-0510-44A2-B042-7EF370530C64&displaylang=en

The Visual C++ Team