I'm no electronics expert but I have a situation whereby I want to run a LED off a 240Volt power supply [and before anyone asks, its got nothing to do with Empegs, docking stations or anything of this ilk ;-)) ].

Can you use a ordinary '5 volt' type LED or do you need special 'high voltage' versions to stop the LED shorting out?

And if so, then How big a resistance should the resistor be, and what sort of 'wattage' (1/4 Watt ok)
We are talking a regular (rectangular) Green LED here that runs fine on 3 volts.