The £100 PC

Actually it's $199, and only available at Walmart in the States, but, this is a great package. It does it by running Linux rather than Windows. It doesn't need all the power just to run the operating system, so can be built from cheaper components. From the reviews on the website, it's won some converts to Linux. It has sold out online, but if you're in the US and want one, you might be able to pick one up in store.