I am going to buy either the single or dual 1.25 G4 in two days or so as soon as the ADC program gives me the thumbs up. Can anybody here explain how much faster the dual is than the single? I assume it's not twice as fast. I've heard magazines and people joke about how loud the dual 1.25 is. Is there a chance the single will be signficantly quieter? Can I buy it without a superdrive and add one later if I need one? Thanks for your help!