Please find instructions for download here:
In brief, download choose_version, chmod +x it (Linux, MacOSX, Solaris,
FreeBSD), run it and discover which version (32/64-bit, sse2/sse3)
better suits your system, then download the corresponding installer.
If you get a message such as "<name_of_installer> is not commonly
downloaded and could harm your computer" on Internet Explorer, please
ignore it, click on "Actions" and choose "Run anyway".