Create a folder on your pc named xbox hdd or whatever makes sense to you, create sub folders for the c, e, f, etc. drives and ftp the contents of each to their respective folders. Install the new hdd and use a setup app, I like the new avadisk v1.5 can get it here http://www.eurasia.nu/index.php it will prep new hdd and install some good apps. (be sure to scroll down on menu and read all options when you first boot up the disk)then you can ftp any additional apps, games saves etc. back to the xbox.
and this will require no moding besides the hard drive right all that has been done to my original xbox is a new hard drive with avalaunch and vigalante or somethin like that im trying to make it just a twin to my old one except 160 gig instead of 80..... we have copied every thing to computer now how do put it on the new hd and in the xbox and run it ....ty for your help