As virtualization becomes more common place, more and more of your backend services will be virtualized. It might be helping you now and you don’t even know. Also, I use Virtual PC at home to run great old DOS games like EGATrek
If you want to experiment with a domain environment and be able to completely mess it up and start over from scrath virtualiztion will allow you to do that. You can set up a virtual domain controller, member server and client PC through virtualiztion and then do whatever you want to and reset it to start over if something goes wrong.
I used to have dual or multi boot configurations at home, to run other operating systems, usually Linux and Windows. Now I use virtual machines for the same purpose.