That's fair enough and makes sense I guess as it also allows for human math error, and future expansions! As for the PC power supply, could you show an example as I am concerned about the size of the for my project and I am really keen on this one (http://www.ebay.co.uk/itm/AC-100-240V-to-DC-12V-Switching-Power-Supply-Regulated-Transformer-for-LED-Light-/230844619265?pt=UK_BOI_Electrical_Components_Supplies_ET&hash=item35bf695a01&_uhb=1#ht_3557wt_1037).
Thanks again!