You cannot relocate the Windows directory
Customers who are migrating their desktops from Windows XP to Windows 7 sometimes ask if it is possible to install Windows in a directory other than C:\Windows. They point out that in Windows XP and earlier, you could configure the TargetPath property in your unattend.txt answer file to install Windows into a different folder such as C:\MyOS if desired. Unfortunately, the TargetPath property not available in the unattend.xml answer file in Windows Vista and later. The reason for this is because beginning with Windows Vista, Windows is now installed as Windows Image (.wim) file directly onto the hard drive, so there is no way you can customize the location of the Windows operating system files because they are already laid out in the image.