I think enough people have advised you to get a good branded PSU, at least 500W such as the OCZ, Tagan, Enermax, Corsair, Seasonic. The OCT is only £32 compared your unbranded choice at £27
Most PSUs have their max efficiency at between 50% to 70% of maximum load so it does help to have a little in reserve.
Are you goign to keep posting till someone says...okay buy a cheapo unbranded 250W PSU?