Chromium OS is an open-source, linux-based operating system, designed by google to work with web based applications. Its quite a simple one really, and not the sort everyone would like, in fact, the only application it comes with is a browser (though of course you can install more apps.)
Anyways if you feel like trying it, there are two ways to do so. The first is to download the disk image, burn a usb or dvd with it and boot with it. But if you dont wanna take any risks, you can try it on virtual box. All you need is virtual box, and the Chrome OS Virtual Disk.
The Process is simple. Start Virtual Box and create a new Machine. Select Linux Ubuntu as the OS Type, and when you come to the “Hard Drive” part, check “Use an Existing virtual hard drive file, and browse to the one you just downloaded. That’s it.
Now start the machine, the configuration process would hardly take a minute. Then just login with your google account.