if you haven't done that yet I should warn you:
that different manfacturers sometimes color their wiring differently. one black wire can be different than another (I have seen this with different supplies in the past 6 months)
that dell does it entirely differently (at least for a while, not sure about now) with their wiring. you have to hand redo a reg atx supply to work on a dell board for example
and if you do do this, be sure you don't use bare wire and electrocute yourself.