We recommend John Lewis for new computers, components and peripherals. John Lewis offer a 2-year guarantee on all new computers. They also offer a series of buying guides:

Desktop Computers:
http://www.johnlewis.com/Magazine/Feature.aspx?Id=10

Laptop Computers:
http://www.johnlewis.com/Magazine/Feature.aspx?Id=18

We also recommend Novatech who are based in Woodley, near Reading. All Novatech PCs are built and finished in Britain at their Portsmouth production facility. Novatech has topped the annual Which? Computing desktop PC reliability survey.