I read and learned from here that the current 85watt magsafe AC cords that come with macbook pros may not provide enough power, & when plugged in & with the mac under heavy load may still dip into the battery reserves. would an external hard drive plugged into the mac via firewire or usb with an AC cord that also may not provide enough power to the hard drive make an additional draw on the mac? i read that some enclosures do not & someone had actually bought a 6 volt monitor power cord to use on their hard drive enclosure, I think this was about earlier versions of the macally enclosures. how can I be sure my enclosure's power cords are providing enough power to my hard drives? & in turn avoid drawing too much power from my laptop?