I have a retail Ultimate disk. I made a copy and deleted the ei.cfg file for my own uses, which lets you chose which edition. I need a disc that installs Pro only. I edited the efi.cfg to with notepad to say pro instead of ultimate, but it still installed ultimate (figured there was more to it). So I downloaded this tool (from here) that is supposed to let you change the version, but I keep getting an unexpected output size error. I installed 7 Pro in this particular computer (I'm selling), and everything is on the up and up (except the MB is old and I had to make the install disk with the Vista boot, code 5 error otherwise) but I want to give them a backup disc for reinstall (especially because of the code 5 error) that is Pro only. I've spent hours researching this and I don't care squat about MD5 and such. I just wast it to install Pro with no other options... the MD5 can't ever match on this because of the boot being changed.