Hi,
Chromium OS is a lightweight OS designed by Google primarily for accessing the internet on a low-powered machine. As such, the initial release did not include support for 64-bit systems. But the release was open source, and the OS has already been ported to 64-bit systems. Note that the release is unofficial and "pre-alpha," but it is available.
Chromium OS Now Available For 64-bit Systems
Moderator: Site Mods