Let me clarify:
"...it is best to make from within each computer's own MR (whether 6 or 7, whether free or pay-for) the rescue USB and the rescue DVD; I found it best to have both a USB (8GB is enough) and a DVD boot -- because sometimes the computer will not boot one but will boot the other -- go figure..." -- my earlier comment
My follow-up comments are directed at making two boots -- a usb boot and a dvd boot.