If you just want to copy it you can do it with Gparted from the live CD.
Just plug in your external and boot up so that the CD OS can access both. It is a fairly long process but a simple cut/paste.
You will need to fix the /etc/fstab to match the new home. Your uuid info on the new drive is easy to get;
You will also need to run;
I would do that after rebooting to the live CD with the internal drive turned off in bios or just unplugged. That will make the external your "a" drive and will boot on anything that will boot from a usb device if the bios are set to boot from the usb.
That will have to be done in a chroot use the directions here;
You will find it in the contents box (number 12) under "reinstalling grub".
Piece of cake. Great way to have an OS (or 7 in my case) that you can just plug into the computer of any interested person and let them use it at real speed. Also fun to let them rummage though their MS files with a free hand. Then boot to Win whatever and let them try and read any of yours. Good comparative security demonstration.