With Wubi, it has never been so easier to install Ubuntu under Windows. Youcan install/uninstall Ubuntu just as simple as a common software under Windows!
To get the latest version of Wubi , go to http://wubi-installer.org/latest.php(You can find Wubi in Ubuntu’s image now ! if you have downloaded Ubuntu 10.04, you needn’t have this additional downloading. )
To get the latest version of Ubuntu, simply go to this URL:http://www.ubuntu.com/getubuntu/download
In fact , to install with Wubi, you can simply browse the Ubuntu iso you have downloaded , then choose the partition you wanna installed. Waiting for 2 times reboot , you can experience Ubuntu 10.04 now!
As usual, I will pick some info from Wikipedia to introduce you more about Wubi:
The goal of Wubi 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 is not a virtual machine, but creates a stand-alone installation within a loopmounted device, also known as a disk image, like Topologilinux does. It is not a Linux distribution of its own, but rather an installer for Ubuntu.
While Wubi does not install Ubuntu directly to its own partition this can also be accomplished by using LVPM, the Loopmounted Virtual Partition Manager, to transfer the Wubi-generated Ubuntu installation to a dedicated real partition, including a bootable USB keydrive. The advantage of this setup is that users can test the operating system and install the drivers before they install it to a dedicated partition (and avoid booting and functioning risks).
Wubi 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. 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, Lubi, uses Linux as the host system instead of Windows. A version for the Mac OS as host, Mubi, “will eventually be supported.”
But it is more recommended to have a check on its official FAQ page: