If you edit the ISO file before you burn it, and delete the ei.cfg file from the sources folder, you can create a universal install disk. Instead of being locked into one version you will get a menu to pick which version you want to install and it will except OEM or Retail key. Your product code still needs to match the version you chose so you can't install Ultimate and then enter your Home Premium key, it will be rejected. All 32 bit DVDs contain all the 32 bit editions, and all 64 bit DVDs contain all the 64 bit editions. The ei.cfg file locks it into one edition and determines if its OEM or Retail. I made one of each and put them on bootable thumbdrives. Saves a lot of time when working on PCs for friends and family. The installs are wicked fast from thumbdrives too.