When downloading firefox from the website http://www.mozilla.org/ you get the 32 bit version and not the 64 bit version.

You can download the 64 bit version at:

ftp://ftp.mozilla.org/pub/mozilla.org/firefox/releases/14.0.1/linux-x86_64/en-US/

Installation

Extract the file and copy the contents to /opt/firefox/ you can start firefox through gnome-console (/opt/firefox/firefox)

Dependencies:

yum install libstdc++