This is repost from http://www.blogsdna.com
Like Windows 7 Public betas Microsoft has made the first Windows 8 Developer Preview build publicly available for download to all Windows enthusiast. Unlike Windows 7, Microsoft did managed to keep tight lied on Windows 8 leaks and it was worth the wait for first official preview build since all the new Metro UI and features can be seen on in this Windows 8 Developer Preview which Microsoft demoed today at Build conference.
Windows 8 Developer Preview is available in ISO format for 32-bit and 64-bit OS. Also Microsoft had made Windows 8 Developer Preview Build along with developer tools (x64) ISO. It should be noted that developer preview is pre-beta version hence it may or may not work correctly and should be available on production machines.
All the machines capable of running Windows 7 should be able to run Windows 8 developer preview without any issue however if you are wondering what are the idea specs for running Windows 8 then check the below list,
1. 1 Gigahertz (GHz) or faster 32-bit (x86) or 64-bit (x64) processor
2. 1 Gigabyte (GB) RAM (32-bit) or 2 GB RAM (64-bit)
3. 16 GB available hard disk space (32-bit) or 20 GB (64-bit)
4. DirectX 9 graphics device with WDDM 1.0 or higher driver
5. Taking advantage of touch input requires a screen that supports multi-touch
In order to install Windows 8 Developer Preview you would require to burn ISO files on DVD. You can use Windows Disc Image Burner which comes with Windows 7.
Download Windows 8 Developer Preview Build ISO