The only problem with James' suggestion is that SQL 2005 is not supported with Server 2012. Which I was a refrained from it in the first place. Of course, you could pay someone to setup the instance for AC and migrate the databases, but that could get costly. I'm sure AC will be upgrading sometime soon.
http://support.microsoft.com/kb/2681562That means while you can use Essentials to manage the network, you will not be able to run AC on either virtual machine since Server 2012 Essentials also runs on the same Server 2012 core that the Standard edition runs on. Not to mention you'll have to deal with the issue of CALs and whatnot.
What you could do is follow James' suggestion and get SBS 2011 Essentials instead in conjunction with Server 2012. The main reason I advised against it was the price. SBS 2011 Essentials is only $400. Server 2012 will be double the price.
If you're bored give the Hyper V Server a try.