In this Video tutorial I used Ubuntu 11.10, but the same applies to, any previous or future version of Ubuntu. Actually, you can install any Linux distribution this way. 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.
1. After you launch VirtualBox from the Windows Start menu.
2. Click on New to create a new virtual machine.
3. When the New Virtual Machine Wizard appears, click Next.
Note: You can call the machine whatever you want. If you’re installing Ubuntu, it makes sense to call it Ubuntu, I guess. You should also specify that the operating system is Linux.
4. VirtualBox will try to guess how much of your memory (or RAM) to allocate for the virtual machine. If you have 1 GB or less of RAM, I would advise you stick with the recommendation. If, however, you have over 1 GB, about a quarter your RAM or less should be fine. For example, if you have 2 GB of RAM, 512 MB is fine to allocate. If you have 4 GB of RAM, 1 GB is fine to allocate. If you have no idea what RAM is or how much of it you have, just go with the default.Click Next.
5. Then you do want to Create new hard disk and then click Next.Click Next again.
6.. A dynamically expanding virtual hard drive is best, because it’ll take up only what you actually use.
7. Ubuntu’s default installation is less than 8 GB. If you plan on adding software or downloading large files in your virtualized Ubuntu, you can make it larger. Click Finish and wait for the virtual hard drive to be created.Click Finish
8. The next thing to do is to add the downloaded Ubuntu disk image (the .iso) boot on your virtual machine. Click on start you’ll see a little folder icon. Click that, and you can Browse for the Ubuntu .iso you downloaded earlier.Once you’ve selected it, click OK.
9. Once it’s started up, just follow the regular installation procedure as if you were installing Ubuntu on a real hard drive (instead of a virtual one).
10. Afterwards, in order to use your virtualized installation (instead of continually booting the live CD), you have to delete the IDE controller by going to settings,Storage delete the IDE controller.