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How to Run Two Operating Systems on One Hard Drive

written by: Lucinda Watrous•edited by: Tricia Goss•updated: 2/16/2010

If you have ever wondered or need to know how to run two operating systems on one hard drive, then this article is for you. Taking you through the steps of multiple operating system installation on one HDD, without crashing or risking harm to your system.

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    Having two operating systems has its pros and cons. Before explaining how to run multiple operating systems, let us take a look at the reasons why you would want to run more than one operating system on your hard drive.

    Security. If one system crashes, you still have the other one. This means that you will not lose files! Not losing files is a very good thing.

    Two Computers in One. With two operating systems, it's like having two computers on one hard drive. You can keep things separate, and try new operating systems without risking harm to your main system.

    Compatibility. If you are worried about your computer's peripherals being compatible with your new operating system, then you can be sure that they will still work with the other one!

    Now, we can't go on without mentioning the drawback. The one drawback to running two operating systems on one hard drive is the space it takes up. If you have a large hard drive, it negates this drawback!

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    Things You'll Need

    • Operating System Discs
    • Software Discs
    • Back Up Media: CD's, DVD's or External Hard Drive
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    Step One

    Backup any files you do not want to lose, because you are going to have to re-format your hard drive in order to have it run more than one operating system. You can do this by enlisting the help of an external hard drive, or burning a bunch of CD's or DVD's.

    If you have any unpartitioned space on your hard drive, see this article How To Install RAM on your Desktop PC for assistance.

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    Step Two

    Now that you have all of your important data backed up, you are going to want to reformat your hard drive. Before reformatting your hard drive, you need to be sure that you have your operating system discs, and the discs for any software on your computer, because you will lose all data.

    To reformat your hard drive:

    • Insert your Windows XP OS disc into your computer. Boot your system, and update your BIOS settings to have the computer boot to your disc drive.
    • Allow the disc to load. Press ENTER to move to the next screen after the "Welcome to Windows Set-Up" screen.
    • Press F8 to accept the Windows Licensing Agreement.
    • Windows will then detect the previous installations, and ask if you want to repair them. Press ESC to skip repairing the current installation.
    • Your current partitions will be displayed. In the next step, you will set up new partitions to allow for your multiple operating system setup.
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    Step Three

    At this point, you should see your C: partition. Press D to delete this partition. Press L to confirm the deletion of this partition. Now you'll have your entire hard drive as unpartitioned space.

    Press C to create a new partition. Do NOT use your entire hard drive space when creating this new partition. For the purposes of this article, we are going to assume that you are only installing one other operating system, and so we're going to divide your current hard drive space in half. Enter half of your current hard drive space in MB for the amount of space for this partition.

    Note: 1 GB = 1024 MB Ex. You have a 320 GB hard drive, and you want 160 GB on each partition: 163840 MB

    Repeat this process one more time to setup the second partition which will house your second operating system.

    Note: If for any reason you want more than two partitions, repeat the process with the appropriate amount of space for each partition, but remember to house at least 10-20 GB for each operating system.

    Choose a formatting option. Most people choose to format the partition by using the NTFS file system. Allow each partition to format, and continue installing Windows XP to the first partition, marked C:/.

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    Step Four

    After Windows XP has installed on your first partition, insert your second operating system disc, and boot from CD again. Follow the on screen instructions to install the second operating system to the second partition, usually marked D:/

    You now have two operating systems on one computer!

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    Step Five

    Restart your system, and choose which operating system to boot to. Install your software to that operating system. Repeat the process for the other operating system, and you are good to go!

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    Tips, Warnings, and Other Information

    • Remember to properly back up all your data.
    • Remember to enter your partition space in MB, instead of GB.
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    Other great 'How To' guides from this writer:

    >>> How To Defragmenting Your Hard Drive in Windows

    >>> How To Partition Your Hard Drive in Windows

    >>> How To Install RAM on your Desktop PC

    >>> How To Defragment System Memory (RAM)

    >>> How To Clean Internet Junk from your Computer