Download the file, use CD burning software to write the ISO to a CD and install it the same as you would any other version of windows
You did see the bit at the bottom of your link that says The RC will expire on June 1, 2010. Starting on March 1, 2010, your PC will begin shutting down every two hours.
I wouldn't install it on a main computer at all, if you have a spare one use that!
The virtual PC is a beta, but it's beta software that you can simply uninstall, unlike the beta of windows 7 which would be a real pain to remove if you were to do a proper install of it on your computer.