Hi,On the chapter "System requirements" on the installation manual it's available a supported architectures list [1].
This should guide to chose the architecture to use. Please take a look and tell if it addresses your concerns. 1 - http://d-i.alioth.debian.org/manual/en.amd64/ch02s01.html#id315171 -- Melhores cumprimentos/Best regards, Miguel Figueiredo