Actually, the Neon lights people generally used in computers give off little heat (most people would say negligable) and cold cathodes put off even less. Cold cathodes also are much brighter (you can see the light in day time), much smaller (much thinner anyway, helps keep it more hidden), less noisy, and last much longer (10-20 yrs instead of 10-20 months), but they are much more fragile. So cold cathode is the way to go, but just be careful with them as they break easily. BGmicro is probably the cheapest and best way to get them, the light and inverter cost about $15 all together. Pcmods is much more expensive, but has everything assembled for you with a protective shell to help keep the CC from breaking and a rubber coated inverter to help keep it from shorting.