On the distribution DVD, all of the Windows version are stored in the sources\install.wim file. If you locate it and run "imagex /info install.wim" you'll see the images listed. 1=Business, 2=HomeBasic, 3=HomePremium, 4=Ultimate, etc. InstallFrom sets the path to the install.wim file as it will appear in the WindowsPE session and the meta data "image/index" is specifying which image in the file to extract to the "InstallTo" location. If you run the BDD, it takes care of this for you.