constant error

I'm trying to install 64bit Firefox but I get the attached error. As a matter of fact, I get this error with may various software I've tried to install including myFairTunes to name one.

Mozilla for Windows x64 platform: Download

I downloaded the first link
firefox-3.0a8pre.en-US.win64.installer.20070902.exe

I'm obviously using Vista Ultimate x64 version

yes i've seen this as well trying to install x64 firefox

it never did work so i assume it is only compatible with XP x64