I know this may a bit cumbersome, but what about one of those vector portable 12v batteries with a firepod firewire charger. you would need 2 firewire ports on the external drive (or one usb and one firewire). My only question is if you can power at the same time as you are downloading files?
the firepod charger:
http://www.tomatochip.com/servlet/P...supplierID=473&commodityID=4387&searchIndex=0
The portable battery:
http://www.vectormfg.com/catalog/vec018s-pocket-power-p-72.html
the firepod charger:
http://www.tomatochip.com/servlet/P...supplierID=473&commodityID=4387&searchIndex=0
The portable battery:
http://www.vectormfg.com/catalog/vec018s-pocket-power-p-72.html