try from : http://www.mozilla.org/en-US/firefox/all.html

thank you

Hi - that just gives me the option to download the regular file which will detect my 64-bit system and give me the 64-bit version (as far as I can tell)

Thanks anyway.

There is not 64-bit version for firefox, only 32 see:

Firefox 10 System Requirements

64-bit version is only Nightly but it is for testing purposes only, and there is not in release channel, as latest 10.0.

Firefox Nightly

thanks again

Thanks - then my software vendour telling me his software doesn't work because I am using a 64-bit browser and need to use a 32-bit browser obviously doesn't know what he's talking about!