As Microsoft fixed the release date of Windows 8 as Oct 26, 2012, now it is in almost 100 percentage in final shape. Microsoft has released Win 8 enterprise version to download and install for 90 days trial period. You can download this Win 8 copy from here.
Remember this is not a final version and for evaluation purpose and you can not activate this after purchasing activation key. You have to again install non evaluation version. This is for developers to test their hardwares, any issues, and for apps development for Windows 8.
Win 8 will be released in three version two for intel processors Windows 8 and windows 8 Pro and third one is Windows 8 RT that is for ARM processors for touch screen. In windows 8 you can use both the interface, metro style UI and tradition windows 7 style.
The installation method would be same as I have already told in my previous post , you have to install it in other partition of your computer dual boot with win 7 or earlier version of windows. And you can uninstall it as per my previous post.