I originally thought I would have to buy a Chromebook, a laptop with ChromeOS pre-installed. Having recently bought a Samsung N145 Plus netbook, buying a Chromebook seemed extravagant. However, I discovered (through a link on Google+) that you can install ChromeOS for free from the web here for free.
So far, I have followed the instructions to the letter and I have had ChromeOS running on my netbook via a USB stick, although when I boot up the machine without the USB stick in the slot, I seem to have messed up my boot options so that neither the Ubuntu or Windows 7 options appear.
Nevertheless, I am not too worried about this because I have backed up all my important documents and photographs to the 'cloud' via SugarSync and so I will just re-install Ubuntu from another USB stick. I am going to wipe over Windows 7. I don't need it anymore.
I will write up further adventures with ChromeOS over the next few days when I have played around with it some more.