[arch-general] Using install dual iso 2012-09-07 - graphics issue?

I have made a bootable usbkey with the archlinux-2012.09.07-dual.iso file but having tried to boot it, both on an Inspiron 530s and also a Samsung Q35 netbook, there is a blue "graphics" screen but it does not stop and offer me the choice of i686 or x86_64 but carries straight on to boot to the normal prompt. So I can't choose which architecture to use for the install. Does anyone know a workaround to be able to get to choose which of 32 or 64 bit to boot for the install? Or is there a problem with this new install media on some hardware? I have done quit a bit of reading but not seen this issue mentioned in any of the arch wiki or other google searches. Thanks -- mike c