It's not you that needs protecting from "death rays" coming from your PC - it's the quality of reception of any radio/TV equipment you (or your neighbours) may have. An AmigaOne with an 800MHz G4 CPU will radiate EM waves at the 800MHz spectrum from the CPU itself and 133MHz from all the traces in the motherboard. There are some components on the mobo itself to stop this (it weakens the signals going from chip to chip if it's all radiated away), but you need some form of shielding to block the rest. On a radio tuned to that frequency you will hear all sorts of interesting white noise, and on a TV you will get 'snow'.
Cool avatar, BTW :-D