Wubi (Windows-based Ubuntu Installer) is an official Windows-based free software installer for Ubuntu.It can bring you to the Linux world with a single click. It allows you to install and uninstall Ubuntu as any other Windows application, in a simple and safe way. Trying Ubuntu out has never been easier.
For history freaks Wubi was born as an independent project but after 8.04 alpha 5 , it started coming within the iso. The goal of the project is to assist a Windows user unacquainted with Linux in trying Ubuntu without risking any loss of information due to disk formatting or partitioning .Wubi can also uninstall Ubuntu from within Windows. It adds an entry to the Windows boot menu which allows the user to run Linux. Ubuntu is installed within a file in the Windows file system (c:\ubuntu\disks\root.disk), as opposed to being installed within its own partition. This file is seen by Linux as a real hard disk.
While Wubi does not install Ubuntu directly to its own partition this can also be accomplished by using LVPM, a Loopmounted Virtual Partition Manager, to transfer the Wubi-generated Ubuntu installation to a dedicated real partition. The creation of Virtual partition and installation of Ubuntu in it saves your data in c:\ drive and it deosnot let any change happen to your system ,its just that it takes some part of your disk space 
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Wubi also creates a swap file in the Windows file system (c:\ubuntu\disks\swap.disk), in addition to the memory of the host machine. This file is seen by Ubuntu as additional RAM. A related project named Lubi (Linux based Ubuntu installer) is also present which lets you install Ubuntu in Linux host machine. After installation , you will be able to dual boot b/w your own previous Linux and Ubuntu.
Caution:- : Wubi sometimes can create problems with certain hardware and hangs out . The only option at that time to regain your system is hard reboot (CPU reset or UPS shutdown 
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Hardware Support :- intel x86_32 bit version of ubuntu and x86_64 bit versions are supported.
Installation procedure :-
1) The first step is to get your Ubuntu installation Iso image. You can get your copy here . To read more about Karmic koala – Ubuntu 9.10 , please read our previous post.
2)Once you have your ubuntu copy, then burn it into a CD or install via USB drive. For using USB, you will need Unetbootin(Universal Netboot Installer) which you can get it here .After running this software select the option “Diskimage ISO” & just give the location of the image file you downloaded.
3)Now , insdert your CD or USB into your computer. Then , open My Computer on your Windows and goto the Installation CD directory os USB drive. Double click Wubi.exe .You will see an ubuntu menu like this one.
4)Now click “Install inside Windows” .You will get option to select destination , desktop environment , username /password etc.
Note:You must have about 6 gb space free for installation , rather the installer asks for only 4 gb but for a better experience, it is recommended to have larger space.
