The next version of Windows, currently known as Windows 8, was showcased in depth by Microsoft’s own Steven Sinofsky and other members of his team. Teased as a system that would "change everything", Windows 8 indeed includes new usage paradigms that are unheard of on the Windows platform, such a full-screen tile-based user interface and an app store, among others. Microsoft has pledged to keep the Developer Preview fresh by issuing periodic updates.
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Most of you probably just want to check out Windows 8 without making a commitment to installing the OS on its own separate drive (or drive portion). No problem! You can still fiddle with the new OS in an environment that's much easier to remove once tinkering time ends, thanks to the power of virtual machines--applications that let you run a virtual PC inside your PC (cue Inception music).
Go grab VirtualBox and install the default package. Once you're finished, you'll open right into a fresh copy of the application. This is where you'll begin creating your system inside your system.
To start, click on the giant New button in the upper-left corner of the app. Give your virtual machine a clever name and select Windows 7 as the operating system. Make sure that your choice of OS (32-bit or 64-bit) matches whichever version of Windows 8 you downloaded.
Click Next, and you'll be taken to a screen that asks how much memory you'd like to devote to the virtual operating system. The 32-bit version of Windows 8 requires 1 gigabyte at minimum, and the 64-bit version requires 2GB, but the more RAM you can give the virtual OS, the better it will run. Click Next once you've made your choice.