Microsoft never contested the fact that Windows Vista's hardware requirements qualified the latest Windows client as resource hungry, but at the same time, the company did point out that, given the right system, the platform would deliver quite a performance. And performance is the correct word to describe a little experiment put together by Keith Combs, Microsoft IT Pro Evangelist. Combs managed to get no less than 28 Windows operating systems running simultaneously on the same machine, namely 27 copies of Windows Vista Enterprise Service Pack 1 and one Windows Server 2008.

"Twenty Seven Windows Vista Enterprise SP1 Virtual Machines executing courtesy of Windows Server 2008 and Hyper-V. All of this is running on a single laptop, Lenovo ThinkPad T61p with 8GB of Kingston memory," Combs explained. "This time I added another hard drive and split the load. I also used a couple of parent disks, and each VM is executing off a differencing virtual disk. The first pic [toward the bottom of this article] is of all the VMs executing. Keep in mind this is a total of 28 operating systems running on a single laptop when you take into account the parent OS, Windows Server 2008. The second pic shows me killing off the VM's and the freeing up of the memory."

Initially, Combs had tried the experiment with just 14 operating system copies, 13 Vista Enterprise SP1 (six instances of 64-bit and seven of 32-bit) plus the underlying host platform Windows Server 2008 Enterprise x64 with Hyper-V RC1. All the Vista copies are running in virtual machines in the Windows Server 2008 hypervisor.

"Pretty cool, eh? I know you think this is crazy and unusable. I did notice while firing them up under this configuration, that I could easily use 10 client virtual machines with the settings and hardware I used for this test. So some interesting scenarios come to mind with the use of Group Policy, Patch Deployment, OS Deployment, etc.," Combs added.