The high street shop that sounds halfway like butlins is one of the worst for selling cheap non branded PSU's. For the sake of a few quid saving it's just not worth buying those things, it's false economy. A respected brand name PSU such as many of those suggested regularly on these forums is a good investment and peace of mind. If a good PSU blows it shouldn't take out the rest of the motherboard with it like cheaper ones might, at least, that's my understanding. Corsair, Seasonic seem to be the best. XFX are good too. I've got an XFX core edition pro 650w but OCuK seem to have stopped selling XFX.