Thanks Ynneb, I'm clear now with what's required. Dont worry about the transformer guys details, I origionaly wanted them because I didn't understand how a power supply worked and the idea of making my own seemed all too hard but after spending some time trawling the net for info I'm feeling confident about building my own. I guess there are two advantages, one being a cost saving and the other being a good educational opportunity.
Thanks
Splint