If you want to experiment with Windows 8 without having to sacrifice a physical system, you can boot Windows 8 from a Virtual Hard Disk (VHD) in Windows 7. Although you could use Hyper-V, I believe it's better to use real hardware to see how Windows 8 interacts with drivers.
Here are the steps to boot Windows 8 from a VHD in Windows 7:
1. Make sure that you have enough space (50GB to 60GB) on your computer's hard disk.
2. In the Disk Management console in Windows 7, create a VHD. Format it as a fixed-size disk with 60GB. (If you're unfamiliar with how to create a VHD, see the TechNet article "Create and Use a Virtual Hard Disk on Windows 7."
3. Download the Windows 8 Developer Preview ISO file at msdn.microsoft.com/en-us/windows/apps/br229516.
4. Install Windows 8. At some point, you'll be prompted to select a hard disk for the installation. You want to install Windows 8 on the VHD, so do not select a hard disk. Instead, press Shift+F10 to go to a command-prompt window. At the command prompt, type DISKPART and press Enter. Then
run the following commands:
DISKPART> select vdisk file=d:\VM\Win8.vhd DISKPART> attach vdisk
5. Press Alt+Tab to go back to the disk selection window. Click refresh. You should see your new VHD listed. Select the VHD. You'll get an error message that states Windows can't be installed on this disk, but you can proceed with the installation.
6. After some time, you'll be asked to reboot your machine. Do so.
Windows 8 will automatically create an entry in the boot manager, so you don't have to use BCDEdit to add the entry, saving you a lot of work. As a result, after your machine reboots, you'll see the new boot loader shown in Figure 1. Click Change defaults or choose other options at the bottom of the screen to change the default OS that the computer will use to boot. You can also change some other options, such as the countdown timer for the selection of the OS and the device that the computer will use to boot.
Figure 1: New boot loader for Windows 8
