When I try to install win8 64bit over winXp 32bit I get this error message: "Your installation media cannot be used to install windows. your current version of windows is 32-bit and does not match the architecture of the 64-bit installation media". I amd using the $69 installation disc and this computer is 64-bit cabable.
You cannot upgrade from a 32-bit operating system to a 64-bit operating system.
You need to boot from the disk and perform a clean install.