Flash media in the 80Gig range will be cost prohibitive. From what I can gather, you are looking for storage that does not require an external power source. You can by an enclosure that will run off of two open usb ports. I have such a solution and this is how I did it. 3.5in (or standard) hard drives require too much power to be run solely off of the usb ports, so you are limited to using 2.5in (laptop) hard drives. They run at less power and the enlosures that they use come with split y usb cables to gather enough power. Below are the two products that you will need to purchase to get a 80Gig storage device that does not require external power. I travel quite frequently and use similiar componants to have a relatively small 40Gig storage device. Duke's link is a much better buy for the storage space, but will require an external power source, where as these will run on two free usb ports. Let me know if you have any other questions.
http://www.tigerdirect.com/applicati...704&CatId=2214
http://www.tigerdirect.com/applicati...522676&CatId=0