
If you want to downlaod the Firefox 3.5 then use the following downlaod link:
For Windows OS :
http://download.mozilla.org/?product=firefox-3.5&os=win&lang=en-US
For Mac OS X:
http://download.mozilla.org/?product=firefox-3.5&os=osx&lang=en-US
For Linux OS:
http://download.mozilla.org/?product=firefox-3.5&os=linux&lang=en-US