Installing a dual-boot with Windows without partitioning

Introduction to Wubi

Many Windows users who are interested in trying Ubuntu are afraid of repartitioning their drives to set up a dual-boot (a dual-boot allows you to choose at boot-up whether you would like to use one operating system or another). Yes, there are other options, like running the live CD or installing Ubuntu as a virtual machine inside Windows. But it’s also nice to know there is still another option—Wubi is a program that comes on the Ubuntu Desktop CD (otherwise known as the live CD) that allows you to install Ubuntu as a dual-boot by installing it as a huge file inside of Windows and then modifying the Windows boot loader to add an entry for Ubuntu.

Installing Ubuntu inside Windows XP using VirtualBox

Introduction
VirtualBox allows you to run an entire operating system inside another operating system. Please be aware that you should have a minimum of 512 MB of RAM. 1 GB of RAM or more is recommended.