Build 64bit binaries on 32bit OS - VS2005

To copy Win32 project settings into a 64-bit project configuration - VS2005

When the New Solution Platform dialog box is open while you set up your project to target a 64-bit platform, click the Copy settings from drop-down arrow, and then select Win32. The following project settings are automatically updated on the project level:

1. /MACHINE (Specify Target Platform) is set to /MACHINE:IA64 or /MACHINE:X64.

2. Register Output is turned OFF. For more information, see Linker Property Pages.

3. Target Environment is set to /env x64 or /env ia64. For more information, see MIDL Property Pages: General.

4. Validate Parameters is cleared and reset to the default value. For more information, see MIDL Property Pages: Advanced.

5. If Debug Information Format was set to /ZI in the Win32 project configuration, then it is set to /Zi in the 64-bit project configuration. For more information, see /Z7, /Zi, /ZI (Debug Information Format).

6. Values of WIN32 are replaced by WIN64 for /D (Preprocessor Definitions).

Ref:
How to: Configure Visual C++ Projects to Target 64-Bit Platforms - http://msdn.microsoft.com/en-us/library/9yb4317s(vs.80).aspx