Just as it was the case for Windows Vista, Microsoft’s latest iteration of the Windows client can also be uninstalled, although “uninstall” does not specifically describe the process that end users will need to take in order to revert to a previously existing copy of a Windows OS. At the same time, also as for its predecessor, Windows 7 can only be removed and the previous Windows platform reinstated in a single installation scenario. Namely, uninstalling the latest version of the operating system is only possible if users installed Windows 7 as a new installation over an earlier version of Windows in the first place.
Obviously, clean installs of Windows 7, where no old OS existed on the hard drive, cannot be uninstalled. The same is valid for users that opted to upgrade from Windows Vista to Windows 7, as well as for those who created multi-boot configurations, deploying Windows 7 alongside older Windows releases.
Uninstalling Windows 7 is only possible if “You used the Windows 7 installation media to install Windows 7 to the same hard disk drive on which you had Windows XP, Windows Vista, or another version of Windows 7 installed. In this scenario, the Windows 7 installation will have created a Windows.old folder that contains your previous operating system and personal files. This Windows.old folder is in the root of the Windows partition,” Microsoft noted.
To add Windows 7 to a system alongside an existing version of Window, you first need to make sure that you have an available partition (or unformatted disk space) separate from the partition that contains the system files for your current Windows installation.
The target partition can be a separate partition on the same physical disk, or it can be on a different hard disk. If your system contains a single disk with a single partition used as drive C, you cannot create a multiboot system unless you add a new disk or use software tools to shrink the existing partition and create a new partition from the free space. (The Windows 7 Disk Management console, Diskmgmt.msc, includes this capability; to shrink partitions on a system running an older Windows version, you’ll need third-party software.) The new partition does not need to be empty; however, it should not contain system files for another Windows installation. Run the setup program, choose the Custom (Advanced) option, and select the disk and partition you want to use for the new installation.
The setup program automatically handles details of adding the newly installed operating system to the Boot Configuration Data (BCD) store.
And how do you edit and configure the Boot Configuration Data store? Surprisingly, the only official tool is a command-line utility called Bcdedit. Bcdedit isn’t an interactive program; instead, you perform tasks by appending switches and parameters to the Bcdedit command line. More »