We had been a proud, satisfied owner of an Apple PowerBook for a little over two years (and a blue-and-white G3 for five years before that) when it all went quickly downhill last November. Our computer started making these frightening, crackling, static, grinding noises, accompanied by nonsensical beeps, and then it crashed hard. We did an "erase and reinstall," which bought us about two weeks. Then, we had to pay our first somewhat quick......