"Ubuntu 12.04 LTS (Precise Pangolin) is the current Ubuntu Long Term Support (LTS) release, made available on schedule on 26 April 2012. Ubuntu 12.04 is Canonical's 16th release of Ubuntu and its fourth long term support version." -- Precise Pangolin Wiki Article
This is a step by step guide to install ubuntu 12.04 in Oracle VM.
Before we start, get a copy of ubuntu 12.04 or (ubuntu 12.04.x) .iso file from this link, select PC (intel x86) desktop CD.
1. Start Oracle VM and click on the New Button.
2. Input ubuntu in the Name text field. Oracle VM would automatically search for its version upon text input, but in case it doesn't select the appropriate choice from the Version combo box field. Click the Next button after filling up the necessary fields.
3. Set the memory size to 2048 MB (roughly 2GB) RAM, and click the Next button.
4. Select Create a virtual hard drive now, and click the Create button.
5. Select VDI, and click on the Next button.
6. Select Dynamically allocated, and click on the Next button.
7. By default, 8.00 GB is the set allocated vdd space, you can set it to any value you wish. You can also choose where to place your .vdi /virtual drive, just click on the Folder icon with the green caret to choose where to save your virtual drive. Click on the Create button afterwards. Set this to 8GB.
8. Now, select Ubuntu 12.04 from the OS selection panel in the VM V-box Manager window, and press the Start button.
9. If this prompt pops up, click on the folder icon and select your Ubuntu 12.04 .iso file. and press Start (look for your Ubuntu 12.04 iso file!!!)
10. When you reach a dark indigo screen with two icons at the bottom, immediately press your space bar. This screen would appear, choose your Language, and press Enter.
11. Select Install Ubuntu and press Enter.
12. This window will then appear, click on the Continue button.
13. You (may) download these updates while installing (if so, click on the check box that says so). Same thing with other proprietary plug-ins like the Fluendo MP3 plugin. But if you'd rather not (and install / update it later), just click on continue.
14. Click on Erase disk and install Ubuntu, and click on the Continue button.
15. Click on the Install Now button.
16. Along the installation, this would appear, select the city closest to your timeline.
17. This screen would appear, click on the Detect Keyboard Layout button (answer the series of questions) and press Continue.
18. Input these text fields, and press Continue. Input using your own computer name, username and password.
19. This might take a while, be patient. Make coffee, or take a bath or something.
20. Once this prompt appears, click on the Restart Now button.
21. The installation screens would appear. Press the Esc button, and select 'Boot from first hard disk'
22. When you reach this screen, you have successfully installed Ubuntu 12.04 on Oracle VM. gz!
23. Lastly, click on the Devices menu, under CD/DVD devices, click on Remove Disk from virtual drive, and click on force unmount afterwards (so that you won't boot from your .iso file anymore).
