You probably have not done a custom install of VS2005 to include the "X64 compiler and tools" subcomponent of Visual C++.
1. From Control Panel > Add or Remove Programs, select Microsoft Visual Studio 2005 (or 2008) > Change/Remove. The Visual Studio Maintenance Mode window will appear. Click Next.
2. Click Add or Remove Features
3. Under Select features to install, expand Language Tools > Visual C++
4. If the box X64 Compiler and Tools is not checked, check it, then click Update. If the box is already checked, click Cancel.
