This would be a SUPERB fonctionnality.
Let me get that right before I get to excited: you keep your internal drive as it is for, say, windows, then you have the ability to boot from the, say, usb or firewire external Hard disk containing your nice Linux OS? Did I get that right?
And you don't need to partition in any way your internal hard disk!

If it is what you mean, that would be SUPERB. A truly portable operating system that you could even -I am pushing my luck here- use on any computer. I am very interested!

Keep me posted.

On the same theme, Demon Worship, do you know how I can find out if my bios supports booting from usb hard disk?

Thank you.