Having dual boot for your computer is like having a permanent ERD installed.
You have a computer that you want to install a second Operating System on. Say you have Windows XP installed and want to test Vista or Windows 7 / 8 before you upgrade to the new OS.
With out buying a new computer or say having a Virtual Computer you would set up your computer to boot in to another OS. It is called a dual boot or multi boot system.
How would you go about making your computer a multi boot system?
Well it takes a little work but in the end you will have two operating systems on your computer.
What you need to do Dual/multi boot for your computer:
When you want to do a Dual Boot System you need to install the oldest OS first.
The reason is that the older OS will not know about the newer OS's boot loader. If you load the newer OS then the older OS. The older OS will overwrite the boot loader for the new OS and you will have to repair the Boot Sector for the newer OS to load. Then you will have to modify the Boot Loader to see the older Operating System.
To get around this load the older OS then the newer OS, this will save you some time and work.
Space for the new OS, if it is Vista or Windows 7 / 8 you need a minimum
If you are a VM Ware user and want to experiment with the XP / Vista dual boot start with XP then load Vista or Windows 7 / 8. If you have Vista loaded then load XP on another VM Drive it will over write the MBR and needs to be recovered before Vista will boot.
Dual Boot with VM Ware:
If you have XP installed and want to install Vista to experiment then before you install Vista you need to create the virtual drive you will be using. Then with XP loaded open the Disk Manager, then select you new drive and create a partition, you don't want to format or add a drive letter, just create the partition. Vista or Windows 7 can't see a raw partition that is a VM Ware virtual drive. I made my partition 15 Gig because I am only do the load for an experiment, it will not have any applications loaded on it.
To install Vista or Windows 7 with an existing XP installed OS I suggest you back up your hard drive partitions. I suggest you make an image of the XP OS and any associated partitions with either Ghost, Acronis True Image, or any other drive imaging program.
With a hard drive that doesn't have enough open space to install Vista:
Some other techs would say using some thing like Partition Magic to resize your hard drive partition's to make room for a Vista or Windows 7 installation.
Then I make the new partition the size I want it to be, using DOS or the Install CD make the new partition bootable, replace the image back on the new partition. Now you are ready to install Vista or Windows 7 on the empty space.
Before installing Vista or Windows 7 on the empty space start XP (you will want to do this anyway to make sure the OS image is good).
Go to Drive Manager, on the drive you resized make a partition the size you need (for Vista or Windows 7, I suggest a minimum 20 Gig or up to 32 Gig). Do not format or assign a drive letter to the partition, Vista or Windows Seven will reformat it when you install the OS.
Installing a new hard drive for the Vista install:
Normally Vista or Windows 7/8 will see the raw partition and will install with out problems but if you start the install and get to the point where you select the new drive and the installation process will not allow you to go forward. In this case I would use the same method above.
Once installed on any of the above scenario's you will see this screen when starting your computer:
One of the neat things about Vista/Windows 7 boot manager is the Diagnostics
So what does the Vista/Windows 7/8 boot.ini look like?
Sorry it doesn't have one. You need a special file called a boot manager to modify the boot settings. The boot manager is named bcdedit.exe. This is a command line editor with the normal MS syntax (commands) that take a degree in Geekdom to use. I recommend a program such as the one listed below.
What about Windows Seven/Eight (Win 7/8)?
Well it is pretty close to Vista with a few changes -
This is a Dual Boot for your computer with Win 7 and XP.
If you press F8 then you get this menu -
The notable additional lines are -
Repair your computer
The lower seven lines are for Beta Testing and will not survive to the production environment when the product is released for sale to the public.
If you select Repair Your Computer you will get the following screen.
You need to have a user ID that has Administrator's rights to log on.
Enter the User ID and Password.
The you will be at the Repair and Diagnostics menu.
What can you do with this menu?
These are the changes that Win 7 is bringing to the boot menu.
You need a special program to view the contents, it is not a text file, one of these will let you view and modify the Boot Configuration Data store.
Using a commercial program to accomplish the dual boot for your computer:
VistaBootPRO (Note: You will need .net for XP, the install program will open the download page for you)
Vista screen shots:
OS Entries, this is where you can change the startup sequence and a few options.
This dual boot manager works with Windows 7 also, but you have to back up the registry before YOU modify the boot settings!
Dual Boot for your computer instructions pre Vista:
To add another OS to the boot.ini for your OS besides Vista you have to modify the boot.ini for the original install of XP to read:
Normal Windows NT / 2000 / XP boot.ini:
Notice that I have added on a Windows 2000 and a DOS partition to show you how the boot.ini would look for more than two Operating Systems.
If you want to have a boot menu when your OS starts you can use this for an example, this is not a dual boot but a normal boot where you can select the startup the same as pressing F6:
The menu, as you can see the different ways you can start your computer:
Pressing the F8 will bring up the 'Safe Mode' menu:
As you can see it is possible to have more than one or two different Operating Systems on your computer.
If you are having problems getting in to the Safe Mode because your computer startup is too fast to get the the F6 key you can add this to the boot.ini to bring up the startup menu just above this line:
This will load the menu then you can select what you want to do instead of restarting multiple times trying to get the F6 key to bring it up. Once you have done what you need to do you can remove it if you don't want the menu to come up all the time.
I will make a recommendation:
Backup your hard drive before you make any modifications for your dual boot for your computer, an image of the partitions is the best way to do this.