Nuke it... No seriously. It looks like a machine you might find in an old nuclear silo or something. Do a militaristic kind of mod on it. Using toggle switches and lit buttons where the keyboard is that have various control designations (Launch button and so forth). Lose the monitor that's in there and install an old oscylliscope or something, or just put in a cheap monitor and run a scope looking graphic to that from something. <Shrug>. Paint it flat black, get some warning stickers of some sort to put on it that fit the theme, put the PC in the guts and mount an LCD monitor that flips DOWN on the top of it so you can get it out of the way when you're showing it off. Use one of those keyboards that project to the desktop instead of an actual keyboard to keep it minimalist.
I'm wondering when the first LOST mod is going to be done. You know, someone get an old Apple and build the rig from the hatch.