VirtualBox 

To import a virtual appliance in OVA format:

1. Download the file ubuntu11.10.ova using the link http://hostel.ufabc.edu.br/~marcelo.nascimento/software/ and save it to your hard drive.

1. Start your VirtualBox software and select "File -> Import Appliance" from the taskbar at the top of the window. 

2. The "Appliance Import Wizard" window will appear. Open the file dialog and select the file ubuntu11.10.ova.

3. The wizard will display the virtual machine in the OVA file. Upon clicking Import, the disk images will be copied and the virtual machines will be created. User can double click on the description items to configure the settings of the VM. 

4. Thus, access a terminal and type:

VBoxManage startvm ubuntu11.10