The best thing for my situation would be to get a DVD burner and burn the ISO to it and install that way. Installing a disk image to a HDD via UNetbootin does not seem to be possible (may work for pen drives and comps who's motherboards are capable of booting to USB drives, but not mine). I've tried the software on the link of the Hack5 video and my external HDD is Fat32 but way too much of a challenge.
I would like to suggest to the BT Dev team that it might be better to abandon including a full blown OS in Backtrack 4 and stick to their knitting of compiling a great Pentest distro or software package or make a distro model similar to Unbuntu (where the core OS can be burned onto a CD instead of a DVD) or, setup a distro something similar to the way PartedMagic is set up (where the Linux OS is a basic GIU but having the great tools that BT has).
But I'm far from being a developer or a programmer so I have no insight as to what goes on into creating software like this. I'm just an enduser with about 25 years experience of using computers.
I would like to say thanks to BT as it has finally opened me up to Linux and I'm on the path of leaving the Microsoft OS!!!
BT is awesome and the help on here has been great!
Keep up the great work!