Install Windows 8.1 Preview
Here: Get the update
UPDATE: Download the ISO
Get Visual Studio 2013 preview too.
Details here: https://windows.microsoft.com/en-us/windows-8/download-preview
Follow these steps to download Windows 8.1 Preview:
Tap or click Get the update on this page, and then follow the instructions.
Restart your PC when prompted, and then tap or click the message that appears to get the update from the Windows Store.
In the Store, follow the instructions to download and complete the installation.
Note before you download: If you don't have recovery media, we recommend that you create a USB recovery drive before you install Windows 8.1 Preview so that you can go back to Windows 8 if you need to.
If you're running Windows 8 Enterprise or the Windows 8 Enterprise Evaluation on your PC, you'll need to download the Windows 8.1 Preview ISO files.
You can find system requirements, support options, and additional information in the FAQ and in the links on this page.