Open Source OS
Open Solaris
Solaris is a Unix System V derived operating system develomped by Sun Microsystems for delivery with there hardware. For a number of years Sun has been moving from providing predominently close, proprietory hardware and software to embracing Open Source.
Linux
Linux is a free Unix-type operating system originally created by Linus Torvalds with the assistance of developers around the world. Developed under the GNU General Public License, the source code for Linux is freely available to everyone. I’ve included links to five of the most popular distributions, the list is by no means exhaustive, but any of these distributions is a good place to start.
I’ve removed links to Debian and Ubuntu due to a vulnerability found in Debian that is inherited by Ubuntu. For the reasons I stated in the post, I’m no longer using or recommending Debian derived distributions.
Free BSD
Free BSD is a free, Open Source derivative of Berkely Software Distribution.
QEMU
QEMU is an open source processor emulator that runs under Windows and Linux. It is capable of running virtual Linux and Windows installations.