I used dism to mount install.wim for Windows 7 Ultimate. I added updates and some drivers. This all goes successful without any issues. I used Index of 1 as the install.wim is Ultimate only after SP1 integration a couple of years ago and has only 1 index now. However, when I try and unmount it and commit the changes, using the command Dism /Unmount-Image /MountDir:F:\WIN7_Mount /Commit I receive an error: 87 stating The unmount-image option is unknown. So I am frustrated and try to find a different way to unmount the image while committing the changes. So I find imagex and run imagex /unmount /commit f:\WIN7_Mount and it appears to have committed the changes and unmounted it successfully. Now the question is, was this an ok thing to do, or will I have problems with the install.wim file. It went through the committing image and then unmounting image processes? AM I ok, or is it bad to use imagex on a .WIM file that was mounted using dism. I only used imagex to unmount it because for whatever stupid reason, dism was fialing to unmount it.