VMWare Hypervisor ESXi 5.x is a free virtual software package.
If you are familiar with using VMWare Workstation than you will love this. When I found out this was free I built a small VMWare server box with 2 Intel Pro 1000 NICs and then installed the ESXi Hypervisor 5.1 to a 120 GB SSD. I then used my TS 469PRO QNAP NAS and made a whole tonne of iSCSI LUNS and setup multiple server, linux boxes, workstation and test machines using the hypervisor to host the Guest but putting the Guest HDDs on the QNAP NAS.
I will be writing some Blogs on using the QNAP for iSCSI and VMWare Hypervisor ESXi 5.x Guests to make your own test lab.