Google Chrome

Simple how to here:

http://lifehacker.com/5801328/make-your-own-chromebook-on-the-cheap-by-installing-chromium-os-on-any-netbook

for this reason, I don't really see the appeal, why not just buy something cheaper and better specced and put the chrome OS on that?

Exactly! - This why I raised the point about shifting to ARM hardware since the idea was to get the cost down below $200 - But google seems to have changed their thinking on this. Technically for a netbook at the same price you get equivalent hardware with a bit more storage.