How to Install More Than One Operating System on a Computer..

When one operating system is just not enough for your needs, or you have some peculiar need that could be met only when you have the other Windows OS version on the system, you can get two OS simultaneously, provided your computer has sufficient free memory. To know more, go to Can I have more than one operating system on my computer (multiboot)?
The multiboot or dual-boot process facilitates this need. The multiboot process requires separation of computer hard drives partition on each operating system. To know more about the partition, go to Create and format a hard disk partition.
After installing another operating system on your computer, you can decide which one you want to run.

Steps to install Windows using a separate partition

Before installing your Windows OS, make sure that you disable all your antivirus and other applications. Remember to take backup of your important files in CD/DVD or a USB flash drive. Ensure that you have your 25 character Windows product key. You can find the key in the installation disc of your Windows DVD or in the conformation email if you have purchased the Windows 7 online. To know more about the instructions on how to install Windows 7, go to Installing and reinstalling Windows 7.
To begin, follow the instructions carefully:

Turn on your computer so that it performs normally, and then perform any one (that applies) of the following steps:
- If you have downloaded the Windows 7 online, then go to the installation file you downloaded and then click it (on screen it will be identified as an Application file below the Type column).
- If you have a Windows 7 installation disc, then insert the disc. Setup will begin automatically. If it fails to open automatically, select Start button, click on Computer, double click on the DVD drive that has your Windows 7 installation disc, and click on setup.exe file.
- If you have saved the Windows 7 installation file on a USB flash drive then insert the drive on the computer. Setup will begin momentarily. If it fails to start, select Start button, click on Computer, click the drive twice, and double click setup.exe.
Go to Install Windows menu, and select Install now.
Visit the Get important updates for installation page. It is recommended that you get the latest updates on your computer. Doing this ensures successful installation and protects your PC to undesired threats.
Go to Please read the license terms page. To accept the license terms, select I accept the license terms.
Open the Which type of installation do you want? page and select Custom.
Go to Where do you want to install Windows? Page, Select the disc or the partition where you want your new Operating system to install.