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Dual-Boot another Windows 7 on a Windows 7 computer

Last reviewed: July 2009

October 2013: This is the new location for this page on this site. Please update your link or bookmark.

Introduction

This guide shows how to correctly and safely create a natural dual-boot of Windows 7 with a second Windows 7 on a computer with Windows 7 already installed. You can then run either of those two Windows by selecting one from a menu during bootup. No data loss will occur and a third-party boot utility is not used.

In this procedure you need to shrink the Windows 7 drive to make room for the new Windows 7.

32 and 64-bit versions of Windows 7 Home Basic, Enterprise and Ultimate were used in testing so this will also work with Windows 7 Premium and Professional. The computer used was a 32-bit Dell Optiplex with Pentium 4 (2.26GHz), 2.0 GB RAM, 1 TB SATA or 160 GB ATA hard disk.

The procedure used is quite easy and suitable for users of all abilities.


Important Installation Notes

Full Installation CD/DVDs. The Windows you are adding cannot be installed from Recovery or Repair CDs or DVDs provided by some OEMs. You need the full installation or setup version to install a Windows.

Shrinking a Windows 8, 7 or Vista drive. You should use Shrink in Windows' Disk Management to resize the Windows partition. You can read Shrink the Windows 8. 7 or Vista Partition for instructions on completing this task successfully. Use the free GParted Live CD to gain disk space only if you must - read the page Use GParted to Resize the Windows 8, 7 or Vista Partition to learn how.


SUMMARY of Procedure (Advanced Users)

  1. Backup important data.
  2. Create Unallocated space for new Win7 at end of Windows disk (use Shrink).
  3. Install Win7 as new installation on the Unallocated space.

That's it! The Windows boot loader menu will boot Windows 7 and the new Windows 7.

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Details: Install second Windows 7 when Windows 7 is already installed

It's important to follow the instructions exactly as stated and you should have a properly working Windows.

Make your preparations

  1. Backup important data before making any changes to a partition. You can burn files to a CD, clone an image of your hard disk, copy files to a USB flash/pen/thumb drive, or use an USB external drive (a good choice)
  2. Optional: Download NeoSmart's free Windows 7 System Recovery Disk if your Win7 DVD is missing!
  3. Disconnect all unnecessary external devices before you start.

Make Unallocated space for the new Windows 7

The single 160 GB disk usually used in testing initially had: System Reserved (100 MB, Primary, Hidden, NTFS), Windows 7 (150 GB, Primary, NTFS). The Windows 7 drive was shrunk leaving about 40 GB Unallocated space at the end of the disk (to the right). After repartitioning it had: System Reserved (100 MB, Primary, Hidden, NTFS), Win7 (100 GB, Primary, NTFS), new Win7 (50 GB, Unallocated).

  1. Restart computer correctly (close all programs before you Restart computer).
  2. Open Disk Management in Windows 7 (right-click Computer, select Manage, click Disk Management).
    • Right-click your CD/DVD drive(s), select Change drive letter and paths..., and click Change.
      Change the drive letter to K (get it out of the way!).
    • Right-click the Windows 7 Volume (probably C:), and select Properties.
      In the General tab, enter wn_7 as the label for the Windows 7 volume, and click Apply.
  3. In Disk Management in Windows 7
    • Right-click the wn_7 volume, and click Shrink Volume.
      • In Enter the amount of space to shrink in MB: enter enough for new Win7.
      • Click the Shrink button (it may take some time to complete!).
        Note that we are leaving the newly acquired free space as Unallocated.
      If Shrink does not give you sufficient Unallocated space, read how to Shrink the Windows 8, 7 or Windows Vista Partition for instructions or use the free GParted Live CD. Then return here.
  4. Restart to Windows 7.
    • Open Disk Management and check that the change made is correct.

Next Install the second Windows 7

  1. Bootup from the Windows 7 installation DVD.
    • Select your Language, and Time..., and click Install now.
    • In Which type of installation do you want?, select Custom (Advanced).
    • In Where do you want to install Windows?, select the Unallocated space you created.
  2. Restart your computer when installation is complete. Select either Windows 7.
    Label the new Windows 7 drive to w_7a.

The new Windows 7 has been automatically added to the boot menu. Nice!

Congratulations! You have created a natural dual-boot of Windows 7 with a second Windows 7.

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Repair Windows 7 Startup

You will not have any problem if you follow the instructions as stated above. However you might encounter some freak occurrence like a power failure during an installation. Windows 7 will boot again if you execute the following procedure.

  1. Bootup any Windows 7/Vista installation DVD or even from NeoSmart's free Windows 7 System Recovery Disk.
    It must be a 64-bit version if a 64-bit Windows is installed.
    • Press a key when you see Press any key to boot from a CD or DVD.
    • Select your Language and then Time....
    • Select Repair your computer (bottom left of the Install now screen).
      An automatic check of your system will run.
    • Click Repair and restart
      Windows 7 should boot normally (very likely). If not, continue here.
  2. Bootup from the Windows 7 installation DVD again
    • Select Repair your computer again.
    • In System Recovery Options, select Windows 7, and click Next.
    • Click Startup Repair.
    • Click Finish when it's complete, and then Restart.
    • You must let CheckDisk run if requested.
      Windows 7 should boot normally.

If still stuck for a solution, boot again from the installation DVD, select Repair your computer, highlight Windows 7, get to a Command Prompt, use DIR command (DIR C: or DIR D: etc.) to identify drive letter allocations (sizes and Labels will help), and type in:
bootrec /FixMbr
bootrec /FixBoot
bootrec /RebuildBcd
X:\boot\bootsect.exe /nt60 C:
  (where X: is your DVD drive letter, and C: is the installation drive for Windows 7).
EXIT, and click Restart. Remove the DVD.

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Related Reading

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Please remember that you alone are responsible for the consequences of any changes you make to your computer hardware or software.

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