I have done some searching - I guess this question could go into the Win 7, Win 8, or general Tech Helproom forum. So far I have not found a clear answer.

The question is: is it possible on a Windows 7 laptop to install Windows 8 from the "upgrade" in such a way as to have a dual boot setup offering the option of running either OS? And if so, how exactly can this be done? I have a laptop running Win7 and ideally would like the option of trying, or being able to run, Win 8 without losing the original and familiar Win7 OS.

Some websites say this is possible and suggest partitioning the hard drive (C) and installing Win8 in a separate partition. But it is not clear whether this requires a complete, separately-purchased original Win8, or whether it can be done using the Win8 upgrade (as in theory I assume the upgrade would normally use, or overwrite and replace, the existing original Win7 OS).

As a separate but related question, I would also be interested to know - if a dual boot installation is indeed possible using the Win8 upgrade - whether the Win8 OS can be installed and run from a separate external hard drive connected via USB, rather than from a partition on the C drive.