install 64 bit

i have been installing 32bit (suse 9.x) but would now like to try the 64bit version...what parts of my netinstall/autoinst env need to be changed? do i have to have a 64 bit install system to install? I hoped that it was just a matter of adding the x86_64 stuff...but it then only installed the noarch packages...I am guessing I need the 64bit root, kernel and initrd at least...any pointers or info would be great thanks Lee