Microsoft’s Hyper-V virtualization technology will come to Windows 8, marking the first time the software is available in both the server and desktop versions of Windows, Microsoft confirmed today.

Hyper-V, Microsoft’s answer to VMware’s popular hypervisor, will continue to require 64-bit processors, as it always has, while adding new hardware virtualization requirements.

“Hyper-V requires a 64-bit system that has Second Level Address Translation (SLAT),” explains Hyper-V program manager Mathew John in Microsoft’s Windows 8 blog. “SLAT is a feature present in the current generation of 64-bit processors by Intel & AMD. You’ll also need a 64-bit version of Windows 8, and at least 4GB of RAM.”

SLAT is a form of hardware virtualization that is included in newer versions of Intel and AMD processors, such as Intel’s Core i3, i5 and i7 processors and AMD’s Barcelona processors. Hyper-V always required some form of hardware virtualization, but this is more restrictive than the current specs.

If the same requirement applies to the forthcoming Windows Server 8, then some machines capable of running Hyper-V today would not be able to run Hyper-V after upgrading. For example, Intel Core 2 machines meet Hyper-V’s current requirements, but do not contain the SLAT feature.

Some may remember that a Windows 7 virtualization technology, XP Mode, also required hardware virtualization, but Microsoft later removed the requirement because not all Intel processors included the required feature.

Still, the arrival of Hyper-V on Windows 8 is a significant step. Windows 8 will also be the first version of Windows to support ARM chips, but Microsoft did not say whether Hyper-V will be a feature available to ARM machines. (We asked Microsoft for clarification on the SLAT and ARM questions, and will update this post if we hear anything.)

Microsoft promised at its Worldwide Partner Conference in July that any PC running Windows 7 today will be upgradeable to Windows 8. The message was designed to prevent consumers from holding off on PC purchases until Windows 8 ships.

While that is still true, the Hyper-V desktop requirements underscore the fact that not every Windows 7-capable computer will be able to access all the features of Windows 8, particularly given that Hyper-V will also require at least 4GB of RAM.

Despite requiring 64-bit hardware and a 64-bit version of Windows 8, Hyper-V will provide the ability to run both 32-bit and 64-bit guest operating systems within virtual machines. Since Microsoft has been working on getting Hyper-V drivers into the Linux kernel, Windows 8 computers with Hyper-V will be able to run multiple versions of Windows and Linux.

“Hyper-V enables developers to easily maintain multiple test environments and provides a simple mechanism to quickly switch between these environments without incurring additional hardware costs,” John writes. “For example, we release preconfigured virtual machines containing old versions of Internet Explorer to support web developers. The IT administrator gets the additional benefit of virtual machine parity and a common management experience across Hyper-V in Windows Server and Windows Client. We also know that many of you use virtualization to try out new things without risking changes to the PC you are actively using.”

Windows 8 is expected to hit the market in 2012, and Microsoft will reveal more about the next versions of its desktop and server operating systems next week at the BUILD conference in Anaheim. Ars will be there.