FWIW - I have a Virtual Lab setup on my laptop.

1 DC

2 SAN VMs (freesan, 1 demo and 1 live)

1 Cluster (2 boxes)

2 stand alone sql servers (1 sql 2012 1 sql 2008 r2)

1 windows base image

1 old laptop image

and to top it all off

1 OS X VM

Currently I used VirtualBox for the virtualization

I have 16GB ram (not all VMs run at once. For the cluster I would have 4 VMs running at once)

1 256GB SSD

1 700GB spinning disk

You can read my series on it here

http://jasonbrimhall.info/2012/12/24/on-the-twelfth-day/

I still have one last article to finish for that series