How to install openSolaris or Ubuntu via Sun’s Virtual Box?
VirtualBox is a virtualization software offered by Sun under two license categories – open source licence & Personal use and evaluation license. Open source license has some closed-source features and you can read this link to understand the differences between the editions offered.
It is worth the try to use the evaluation version to test virtual environment offered by Sun and its features.
Below is a screenshot of Sun Virtual Box running Opensolaris .iso image.
Some of the other virtual environment tools are virtualPC tool from Microsoft and VMWare.