Depending on how competent you feel about doing a lot of the set-up yourself, Aldi often have some good deals in store. A colleague and I have both bought various computer bits from them in the past and have found them to be good quality at very reasonable prices.
You're right to want to stay away from PC World. One of our better, more knowledgable IT blokes at work tells me he used to work there and that most of the staff know diddly squat about what they're selling. All they're interested in is making sales.