"I will turn down free beer software in favor of freedom software when both exist. If you don't know the difference, that's OK. You cannot see the source code for the video drivers from ATI, for example. You can get them for free but they are not freed. The same with Adobe Acrobat Reader and plugins for the Firefox web browser.
"When it comes to virtual machines for Linux I reach a dilemma. Luckily, I have the free VM for Linux, Xen, running a DNS server on my web site. I say luckily since many people of whom I know cannot get Xen to run..."