Just thought i would give you an update on a problem with my ibook which you all helped me out with a couple of months ago. If you remember, my iBook (tangerine, 300 MHZ - old!) would suddenly shut down with no warning. The battery is definately dead, so clearly it was a problem with the power cord (althought there was advice in this group about the pRam). I have two power cords, and they both displayed the same problem - i did however notice that if i fiddled with the cord, could see a small spark up near where the cord connects to the mac. I also noticed that the silver wire inside the cable seemed a lot thinner in this area than in the rest of the cord.
And so....I took the spare one apart, and saw that in fact this seemed to be the problem - I connected up the wires using a spare bit of wire, and some solder, and sure enough, the problem solved! Did this to both power cords - and now no matter how much i move the cable, the mac stays on - which is a nice change, as it has been dodgy for months, and i couldnt really afford to buy a new cable. As this problem occured with both the main cable, and the spare - i would advise anyone with similar problems, to not immediately go and buy a new cable, but if they can (ie have some wire strippers, soldering iron etc) fix up this fairly minor, but annoying problem.
Hope this helps someone similarly afflicted, both save annoyance and money!