Just ripped apart a old desktop I have laying around gathering dust to salvage the 300W power supply (should be enough for testing).
As I am not an electrical engineer, it took me a while to get any juice out of it though, but the info on this page helped me out (connecting the green wire to ground did miracles.
I also got the "Rostock modified" Marlin ready to be transferred to the Sanguinololu.
Nopheads film will be my little tutorial on how to attach those little connectors to the motor and end stop wires. Once this is done, I can start uploading Marlin and testing.