Microsoft in September 13th, 2011 uncovered the developer preview of the Windows 8 and promulgated that they will release Windows 8 ISO image as a free download for the public.
Interestingly Windows 8 is conformable with non-touch PCs also and even netbooks with Intel Atom processor and at least 1GB of RAM. Does your computer meet this spec? Go ahead and download Windows 8 developer preview.
Thankfully, this time everyone can download Windows 8 ISO-from the official Microsoft website. What you need is to get a Windows Hotmail or Live Mail ID, and then proceed to the link given in the image. Download the 32 bit or 64 bit version of Windows 8 and use the Windows 7 disk utility to burn that ISO file to a DVD.
However you can download it from the links here below.
For this time, it is heard that you have to do a fresh installation.
Unfortunately, some of the Windows 8 features like app store and parts of Metro UI will not work on this dev preview. The minimum resolution required to run Windows 8 Metro apps is 1024×76 pixels.
Download links: Windows 8 ISO direct link- Download 32 bit (2.8), 64 bit (3.6GB).
