If you use FileVault on your main drive or on your Time Machine, here are some tips I picked up on Lion, which might make your life easier. Things may have cha

If you use FileVault on your main drive or on your Time Machine, here are some tips I picked up on Lion, which might make your life easier. Things may have changed, but should still apply to Mountain Lion. On each machine you have, download the Lion Installer app via the App Store. The app seems to be different for different models of Mac. From experience, it seems one model Mac might not be able to use the installer from a different model Mac. Open the app package and burn the ESDInstall.dmg to a USB stick to use as an installer. Using the USB installer, erase the drive as a single partition, and perform a clean install of Lion. This ensures the recovery partition is created on the drive. Launching the USB installer again, format the main partition and then restore from your encrypted Time Machine. The partition you are restoring to is unencrypted so when the restore is complete, reboot your Mac, and manually enable FileVault (if you want it).