Second, virtual machines these days are incredibly easy to set up and
use. Steve Litt posted a link to an introductory article on qemu/KVM
here very recently, I suggest that as a starting point. There is a tool
called "Virtual Machine Manager" (package: virt-manager) that I would
recommend. It is very easy to use, and uses qemu/KVM. Virtualbox from
Oracle is another alternative, though I prefer KVM.
Using a VM takes a little bit of resources, but would give you the
ability to run another distribution without having to reboot. You can
run it full-screen, so you can use the desktop just as you normally
would. For increased performance, you can set the virtual machine up to
use a partition (or logical volume) just as a regular installation,
instead of using an image file.