NSIS (Nullsoft Scriptable Install System) is a professional open-source tool for the development of Windows installers. It is designed to be as small and flexible as possible and is therefore highly suitable for internet distribution.
NSIS 3.03 adds improved 64-bit support for the System plugin, a couple of language file improvements, WinVer.nsh additions and more.
Note that Python 2.7 and above is now required to build NSIS.
Download:
http://nsis.sourceforge.net/Download
Release notes:
http://nsis.sourceforge.net/rn/v3.03