Vista - Ordering Vista 64-bit installation media

Hi,

I purchased a PC with Vista Home Premium preinstalled. It came with no
media. The product key is on the side of the PC and nearly illegible.
I purchased a DVD to upgrade from Home Premium to Vista Ultimate. With
help from the PC manufacturer's download site, I was able to upgrade
to Vista Ultimate 32-bit error free. I still have no installation
media. I wish to install Vista 64 bit. (To best of my understand
upgrade from 32-bit to 64-bit is not possible, only clean install or
custom install). I'm a little confused by my interaction with Windows
site at:

www.windowsvista.com/1033/ordermedia

I cannot seem to obtain the option to order 64-bit media, but I am
given an option to order the 32-bit installtion media which I do not
yet own, only the upgrade media. Do I first need to order the 32-bit
media before I am eligible for the 64-bit media? Do I need to wait for
delivery? Can I order 32-bit media and 64-bit media and put it all on
one credit card transaction?

Thanks for the help.