Has anyone else used any "Virtual PC" or "Virtual Server" software that actually works as you would hope it would (a fully functioning OS running within another "Host" OS).? I would like to hear your thoughts and experiences.
I've used qemu, VirtualBox and VMWare among other things. They work fine with networking. I don't know about 3D but I'd expect getting near-native 3D performance to be troublesome at best.
In my experience it's pretty straightforward (the web is full of HOWTOs and the like) if you understand networking basics, don't mind doing a bit of troubleshooting and don't try to do something unsupported.
If this stuff is giving you too much trouble, you could also get a few old computers for free. Check freecycle or something.
My opinion doesn't count for nothing but something which would matter more for me than having played with Active Directory in a sandbox is the ability to learn about stuff like this without asking anyone as well as the ability to find more appropriate places to ask such questions than SPCR.
And I wouldn't consider having used Active Directory in a sandbox at home (virtual or not) a replacement for hands-on experience with a live network. Obviously I'm not a checkbox-ticking suit so, again, my opinion doesn't count for nothing.
Maybe you can volunteer at some kind of non-profit or something. I wouldn't expect most organizations to be looking for volunteers to do that kind of work but a few might be using Active Directory and have some overworked guy badly needing an assistant. Organizations which can't afford to hire anyone or to outsource are of necessity open-minded about who they'll allow to work on their networks.