Portable Storage Drive

I have a Nikon D200 Digital SLR that uses a CompactFlash (Type I/II) MicroDrive and when I'm in the field I take lots of high resolution images that takes a long time to download through the USB port of a laptop. I would like to be able to just carry a self-contained portable hard drive (i.e. 2.5" hard drive in an enclosure) with it's own battery source and just be able to insert the MicroDrive to a card reader connected to the enclosure and download all the images of the MicroDrive without the use of a laptop. A commercial version already exist but they are very pricey like the Epson P-2000. Basically I want the same functionality of the Epson P-2000 but I want the option to use whatever size drive I choose. How much battery would I need to power a hard drive? Would I have to use some sort of circuitry to transfer the images from the MicroDrive to the hard drive with a push of a button? Does anybody already have any instructions on how to build this?? Any help would be greatly appreciated. Thanks

Well I know there's alot about using CF cards to swap out ipod harddrives so there probably is a way to do it, though this is a confusing one... Nice name by the way, happened to be villain of the day yesterday...
It has been done before like the Epson P-2000 specifically designed to store images from cameras. These models are still expensive for me. I would like a home-built version so I can re-use my old hard drives. Dick Dastardly my all time favorite cartoon character from the whacky races and his sidekick Mutley.
It's probably not that complicated either, I suppose you'd need to know more about the workings of the eposn unit to find out what the craic is...