For what it is worth, I second the hypervisor idea. That is what those
things are for. If you are going to be a sysadmin for your own business,
you cannot shy away from being bold in your learning and investment in
learning new things, or _current_ things, I might add. Thank me later.

I am not too competent with GRUB2, but I am sure I can dig some info
for you. The general idea with GRUB is that it really is something like
a bootloader and a primitive OS. In general, all you have to do is edit
the "grub.conf" file, wherever it lives (typically on a partition like
/dev/sda1 that is typically mounted as /boot on a standalone system).
You put an entry for a particular syste that you want to boot and then
it just makes it appear on the menu at bootime. But the powerful thing
is that you can just walk into a command prompt like a boss and take
care of matters from there. This is how I rescue systems, tweak them,

The tricky thing is to be able to tell GRUB for each entry in that boot
menu where the kernel is. I keep a kernel handy in /dev/sda1 so that I
can just boot, and then throw an "init=/bin/bash" as an argument and I
get a prompt on the root filesystem that I choose (you give another
option for that).

Invest some time in learning the booting sequence of Linux. Then learn
soem about GRUB. Then experiment (preferably with a VM in VirtualBox
or similar), because those boot faster and do not break the system in

Send us your "grub.conf" that is found in /boot/grub of your main system.
I will tweak it for you.