I'm not sure if upgrading from a 32-bit OS to a 64-bit one is possible, you're probably limited to the 32-bit one.
But, all you really need to do is download the ISO of the OS from Microsoft, burn it to a DVD, and run it. They recommend backing up your files and stuff before doing so, though I haven't heard of anyone having any data loss after upgrading.
Though, I upgraded from Pissta, but I assume it works just as fine from XP.







