Chrome OS is at the beta stage. You can download the free Chrome OS Live CD below.
Download Chrome OS 0.8.552 beta (x86) Live CD
602 MB iso, MD5: 9089c4d93f03a3644b1a500aa708c3ba
How to install: Download the iso file and burn it into CD-R. Boot the computer from it and when Chrome OS is loaded, click Live Installer on the desktop. Follow the instructions.
User password: user
Root password: root
SOURCE : GOOGLE