Minimum system configuration
To install any version of Ubuntu Linux Distribution, you must have a 512 MB RAM and 20 GB of hard drive space. GNU/Linux comes in various flavours and each are called as Distro or Distributions. Ubuntu is available in 32-Bit and 64-Bit versions. If your system has 64-bit processor then go for 64-Bit version. You cannot install 64-Bit version in 32-Bit processor. A system with a 32-Bit processor can utilize up to 4 GB of RAM and it is higher for 64-Bit processor. A 64-Bit processor has more memory address than 32-Bit. To utilize all those memory address it is required to install 64-Bit version on 64-Bit processor.
You should be careful while drive partition. If you do something wrong in partition it may end up with formatting Windows files. Follow the below steps to avoid any risks and install Ubuntu OS.
1. Insert Ubuntu DVD into your drive and reboot your computer.
2. In boot screen you will get a message 'Press any key to boot from CD/DVD drive'. Press any key to start Ubuntu installation process.
3. The language selection screen opens first. The selected language will be your system language. You can also change the language settings after installation.
4. After selecting the language you will be asked to select installation mode. There are two modes, one is live OS and the other is full installation. Live OS runs directly from the CD. To run live OS click on 'Try Ubuntu'. To install the OS click on 'Install Ubuntu'. Now I am focusing on installation so I will continue with installation steps.
5. In next step tick the first check box. It will installs multimedia components in your PC or else you will be asked to install manually.
Warning: This may lead to Windows OS formatting.
It is not too complex as it sounds. You have to be patience while partitioning. Follow the below steps to proceed.
1. After completing the above steps a new window opens with several option. Choose 'Specify partitions manually' or 'Something else' whichever you see. Option changes from version to version. There is no risk in choosing this options. Click 'Continue'.
2. Now you can see the partition table with attributes like device, type, size etc. Here you can see the Windows OS installed in your disk. Under the device column you will find 'free space'. Select free space and then click on + (plus) icon to create swap space.
Every Linux OS needs three mandatory partitions - swap, boot and root. Don't bother about its functionality. For swap you need to allocate space which should be double the size of RAM. So below I have given swap size for given RAM size.
512 MB RAM - 1024 MB swap space
1 GB to 4GB RAM - 2048 MB swap space
Above 4GB to 8GB - 4096 MB swap space
Enter the value depending on your RAM in size box. Then select the mount point as swap.
The kernel files get stored in boot partition. Press the + symbol in partitioning table to create boot partition. It should be 250 MB for any hardware. So give the size as 250 and mount point as /boot.
Note: If you are running out of space then give 50 MB in size which is sufficient for any Ubuntu kernel files.
Root space should be larger. You will be using this root space after installing Ubuntu OS. All the software or program you install get stored in the root space. So allocate all the free space to this root. To do this give the size you want and choose / as mount point.
After partition is created, click on the root (/) partition. Then click on 'install now' to install Ubuntu OS. If you click on any other partition, it formats the specific partition and install the OS. So be careful and don't forget to select root (/) partition. This step is followed by creating user. Create a new user and password in the mean while the OS gets install. After installation gets complete, you can see the two OS in home screen: Ubuntu and Windows.
Read How to use Android phone as a bootable USB drive to install Linux OS
I was looking for this kind of article which explains the step by step process, finally I found it. One request to you, please write another such article explaining how to install Windows OS in a PC installed with Ubuntu Linux OS.