Thanks everyone for your help in getting the Mac Mini up and running again.
I'm currently waiting for the keyboard to arrive here before I do anything more, but... turns out I was lucky enough to get hold of a PowerBook G4 yesterday! Installed MorphOS on it, so now I'm back in action again, hehe. Will still try to get the Mini working of course, but I think this laptop will see a lot more use in the future.
Member of Void - An Amiga demo group (website