> I would use separate disks if that were an option but there is room for only
> one drive in the chassis. I bought this sy stem cheap because I need someplace
> to test software BEFORE I install on my primary systems this way I won't be
> destroying my main systems with new software rather just a testing system and
> if things work - - -well then they get moved to their permanent homes
> and if they
> don't - - - HOSED! (and without my main systems getting polluted!)
> Sorry -  - its a good idea but not possible this time.

You do not wnat to use VMs (the safest and easiest), you do not want to hack
your way to boot multiple systems on your own. You seem to want to do this
within the context of how distributions ship out, especially the ones that are
meant for the starting Linux user who is looking for convenience. (Methinks)

if you want to be doing this kind of testing with different disks, why close
the chassis at all... Keep a SATA and a power wire out and keep plugging and
unplugging. Do this until you have learned all you need to know. Maybe this is
the next best piece of advise I can offer to using VMs.

When in college in the 90s, my frankensteined PC had almost all components
resting on eachother inside an open chassis for which I did not have the screws.
My favourite setup was that of a friend, who had the system hanging on the wall
with nails, like artwork.