There are many virtualization programs available for Mac OS X, Windows, and Linux. What is your favorite? I have used many different ones and I really don't think I could have a favorite. I love Virtualbox for its performance and wide variety of Operating Systems. I also like Microsoft Virtual PC because of its VM Tools, where I can drag and drop files to the desktop of my virtual machine. This is really good for virus testers, like me, if you have something downloaded on your main hard disk. So, what is your favorite and why?