x86 refers to the machine type, not the OS type.
x86 is a 'windows' computer, as oposed to a computer with proprietary hardware, like Apple.
All you have to do is burn the iso to a cd using your cd/dvd burner software.
Boot to the cd, and do what you need to do.
The cd will boot into windowsPE, which is its own self-contained OS.
So, it doesnt matter if you have a 64 bit os or not.