Here's the way I would go if I started all over today:
Buy a new server and a volume license for Server 2012.
One Server 2012 license gives you a license for hyper-V and 2 virtual 2012 servers.
The volume license allows you to exercise downgrade rights.
Downgrade one server to Server 2012 Essentials which gives you AD and PC backup for up to 25 PC?s.
Downgrade the other server to Server 2008 R2 and install SQL.
You retain the right to upgrade the 2008 R2 server to 2012 at any time at no charge.
