If you want to run multiple operating systems on a single computer without using a virtual machine, then read on to learn how to dual boot. Before you begin the process, you should decide what operating systems you want to install and how much disk space they need. Note that this is a complicated process. If you are not comfortable with computers or you have never installed an operating system, you should probably gain some more experience first.

This page will explain in detail how to partiton your hard drive and dual boot your computer. It applies only to PCs. If you are using a Mac, this how to may not be very helpful to you. Otherwise, read on to learn how to dual boot your computer.

• Read everything and have a plan before you begin.

• Backup your important data before dual booting.

• Have another way to access the Internet in case you run into problems.

• Move data out of partitons before deleting them.

• Remain calm and try to figure out what went wrong if something doesn't work right away.

• It is easiest to install a second operating system on a new hard drive, especially if you are new to dual booting.

Dual booting is the process of installing multiple operating systems on a single machine. It is different from virtualization in that the operating systems run by themselves, and are therefore faster. However, dual booting, unlike virtualization, cannot run multiple operating systems at the same time.

Having multiple operating systems is useful if you need to run a wide variety of applications that will not all run from within the same operating system. For instance, if you need to run an old Windows 2000 program and a new Windows Vista program on the same machine. It is useful to people and small businesses that need to run different operating systems but cannot afford to have separate computers. Large businesses may find that it is easier to simply purchase a powerful server and run the different operating systems in a virtualized enviroment.

If this is your first time dual booting, make sure you read this entire guide and have a gameplan before starting. This includes knowing what operating systems you are going to install and in what order. It is a relatively complex process, and there is not a "one size fits all" path to take when setting up a computer to dual boot. I have done my best to include most of the situations a PC user would come across when configuring a computer to dual boot (remember, if you are dual booting a Mac computer, this how to is not for you).

• Before you begin, make sure that you have all of the files you need to keep backed up. There is a chance that you will make a mistake and lose your data, so a backup is essential. Refer to How to Back Up Your Computer Hard Drive to complete this important prerequisite.

There is really no general timeframe that fits all situations. However, after reading this how to and doing some research, you may be able to come up with your own estimate on how long this will take. Generally, you should plan for this to take at least a couple of hours.

Finally, remember that this is not something that novice users should attempt, and you will have limited or no access to your computer and files on it during this process, so make sure you do this at a time when you will not be needing the computer. Now, let's get started!

If you haven't installed your first operating system yet, thats ok. You can actually save time by performing this step during the install. When your operating system asks to create a partition, make sure that you do not use your entire hard drive, or that you only create a partition on one hard drive if you will be using a second hard drive for the second operating system.

• If you are installing the second operating system on a new secondary hard drive you just installed into your computer, you can skip this step. Otherwise, you will need to resize the partition for your current operating system, as it probably uses the entire hard drive. To do this, follow these steps:

• Download the Parted Magic Live CD from here: http://partedmagic.com/. Go to the website and download the ISO file.
• Use CD burning software to create a disc from the ISO file. If you do not have software that can do this, CDBurnerXP is free and can be downloaded from here: http://cdburnerxp.se/
• Once the CD is burned, insert into your computer's optical drive and reboot your computer. Upon reboot, it should boot from the CD instead of your hard drive. Simply press enter on your keyboard to start Parted Magic. It will take a few minutes to boot, and during this process, will display various screens, messages, and eject the disc.
• You will know it's complete when the desktop appears. At that point, go to the bottom of the screen, on the taskbar, and select the button that says GParted when you hover over it. (View the PartedMagic website for more information of the other features of PartedMagic).
• In GParted, go to the dropdown in the upper-right corner and select the hard drive that you are going to install the second OS on.
• If this hard drive is a secondary hard drive, you can safely delete the partiton on it by clicking on it and then going to Partition>Delete. Make sure you don't have any data on it, as it will be deleted with the partition. Then click Apply at the top of the screen and wait for the process to finish. (It shouldn't take very long.)
• If you only have one hard drive or you need to keep the partition on the second hard drive, then you will need to resize it. Select it and go to Partiton>Resize. Enter the amount of space you want either before or after the partition (it doesn't really matter which you choose) in MB (You probably should have at least 6 GB, or 6,000 MB) and hit resize. At the top of the screen, click Apply and wait for the process to finish. (It might take several hours depending on what it needs to do.)

About partitions:

When you partition your hard drive, you are assigning a place for each operating system to live. Generally, the operating systems can access data from each other's partitons, but thier files will be placed in their own partiton. Most operating systems require that they have their own partiton for thier files. However, sometimes you can dual boot with only one partition, such as with Ubuntu installed using Wubi. In this case, you do not have to repartition your hard drive, and you can skip this step.

Congratulations! Step 1 is complete!

Step 1 was pretty complex, but now that you have made it to step 2, the hard part is over. However, you still have at least an hour (depending on your OS) before you are done.

• Now it is time to install the second OS. To do this, follow the instructions for installing that specific OS.
• There are a few things you should know first, however. There are two main branches of operating systems we could be working with, Linux and Windows. When dual booting different operating systems, we need to make sure that we install them in the correct order. Generally, we install Windows operating systems first, in order from the oldest to the newest. We then install our Linux operating systems. We do this so that each operating system we install can "see" all of the other ones we have already installed. This allows it to automatically configure the boot loader. If the boot loader is not configured correctly, you will not be able to boot into some or all of the operating systems you have installed.

Finally, when installing the additional operating systems, make sure that you partition the empty space on your computer. You should not have to delete partitions, we already did that in Step 1. Also, if you are going to install more operating systems beyond the second one, make sure you leave room for their partitions.

Almost Done!

Now you are officially dual booting your computer. Check to make sure that you can boot into all of your operating systems. If you can, good! If not, then did you install them in the correct order? If not, then you will need to install a new boot loader. Help with this is available here: http://www.gnu.org/software/grub/grub-2.en.html

Once everything works, you're done! Now you can install your applications and updates in their respective operating systems. Remember to install anti-virus software for each operating system as well.

About filesystems and partitons:

Operating systems generally need their own partiton for their files. However, you can sometimes access the partitons of different operating systems from another OS. Wheather or not you can do this depends on the partiton's filesystem. Different operating systems use different file systems. For example, Windows uses FAT32 or NTFS, while Ubuntu uses variations of the ext filesystem. Depending on your operating system, you may or may not be able to access the partitons of different operating systems. Refer to the instructions for your operating systems to see which file systems they can access.