Windows 10 Preview: How To Try It, Safely

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If you got a laptop or other device for Christmas that came with Windows 8.1 installed, chances are you're still getting to know your gadget and the operating system, and Windows 10 is not even on your radar. Then again, it might be: More than 1.5 million people already have signed up to try Microsoft's Windows 10 Technical Preview. That number is likely to rise in January, when Microsoft has promised to release a significant new Preview build.

If you're the type who does like to live on Microsoft's bleeding edge, you might already be scoping out how to install the Windows 10 Preview on your new device -- without hurting it. But is that even possible? Microsoft has cautioned from the start that users should not install the Preview on production machines. A handful of significant bugs, including one that nuked File Explorer functionality, have testified to the risks.

Luckily for Windows 8.1 users, Win 8.1 includes almost all of the same Hyper-V virtualization technology found in Windows Server. That means rather than simply installing Windows 10 Preview in place of Windows 8.1 -- and accepting the attendant dangers -- you can use a virtual machine (VM) to run it. With Windows Preview 10 running in a virtualized environment that's sandboxed from the core system, any problems should not propagate to the host OS.

Not every Windows 8.1 user can use Hyper-V, unfortunately. There are a lot of device requirements: a 64-bit version of the Pro or Enterprise versions of Windows 8.1; BIOS-level virtualization support; and a 64-bit processor with support for Second Level Address Translation (a.k.a. SLAT, a CPU-level enabler of hardware virtualization that's found in the majority of recent chips). You'll also need at least 20 GB of free disk space and at least 4 GB of RAM. In other words, if you're reading this on a Surface Pro 3 your hardware probably has the chops, but if your new rig is a $200 Windows 8.1 tablet, don't get your hopes up.

But if you have the necessary hardware and want to explore Windows 10 without living dangerously? Hyper-V is an outstanding, fairly straightforward option. Here's everything you need to know to install the Windows 10 Technical Preview using Windows 8.1's built-in virtualization.

Step 1: Ensure Hyper-V is enabled
Before you can install the Windows 10 Technical Preview, you have to create a VM to house it. Some manufacturers enable hardware virtualization by default in some devices. Microsoft does this with the Surface Pro 3, for example. If your device isn't pre-configured for Hyper-V, here's how to activate the feature.

1. Open the Charms menu by swiping from the right edge of the screen on touch devices, or by pressing the Windows key + C if you're using a machine with a physical keyboard.

2. From the Charms menu, select "Settings," then "Change PC Settings."

3. In the PC Settings menu, select "Update and recovery" from the left

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