Liquid nitrogen isnt exactly a system, its a temporary thing that whackos try, lol. In all seriousness though, liquid nitrogen evaporates very quickly, and its not something you can use like water for cooling, also it requires special handling...you cant use it with a fully assembled working computer...if you want to get wild with cooling freon is the way to go, you can build your own if you have the technical know how <its no walk in the park> or buy something like the astek vapo-chill, its reviewed on tomshardware.com if your interested.