If you want to preserve the Dell OEM preactivation for XP Home, you need to do a couple things: As a preliminary matter, your XP Home source CD will need to be an OEM CD, as opposed to a retail CD. If you still have the Dell OEM CD, it has all the files you already need and you don't need to do anything more than insert the CD and run it. However, if you don't have the Dell OEM CD, but have another manufacturer's OEM CD, you can make your own Dell OEM CD in the following manner: First, use a tool like the Magical Jellybean Keyfinder (http://www.magicaljellybean.com/) or Speccy (http://www.piriform.com/speccy) to retrieve the Dell OEM product key for XP Home on a preactivated machine. As far as I know, Dell has used the same product key since XP was released in 2001; however, you should use whatever product key is already on the machine. You will then insert this key into your winnt.sif file in the I386 folder in your XP Home source. Second, run the following script on a preactivated machine to retrieve four files you will need to copy to your I386 folder in your XP Home source: attrib -s %SystemRoot%\system32\CatRoot\{F750E6C3-38EE-11D1-85E5-00C04FC295EE}\OEMBIOS.CAT makecab %SystemRoot%\system32\CatRoot\{F750E6C3-38EE-11D1-85E5-00C04FC295EE}\OEMBIOS.CAT attrib +s %SystemRoot%\system32\CatRoot\{F750E6C3-38EE-11D1-85E5-00C04FC295EE}\OEMBIOS.CAT makecab %SystemRoot%\system32\OEMBIOS.BIN makecab %SystemRoot%\system32\OEMBIOS.DAT makecab %SystemRoot%\system32\OEMBIOS.SIG Copy this script, paste it into Notepad, and name it OEMFiles.cmd. When you run the script, the files will automatically copy to whatever directory OEMFiles.cmd is in; therefore, I usually put OEMFiles.cmd in its own folder before running it. Simply run the script, then copy the four files in your I386 folder in your source. If you need a primer on making your own custom XP CD, look here: MSFN's Unattended Windows Guide EDIT: As for Vista preactivation, it's even easier, and you don't even need an OEM source - just follow orev's guide using his VistaABR tool: http://directedge.us/content/abr-activation-backup-and-restore Supposedly this may work with 7 as well, but I haven't used it yet with 7.