If its making noises, its a good bet your drive will eventually die. In some cases, drives last for several months after making the noise, while in others it may only be a few hours. The best thing to do is probably to copy what you can from it and reformat the disk and see if that helps. You might also want to try another utility such as tech tool before doing this, and see if it helps at all. In any case, backup what you can as soon as possible. THen you can try and figure out weather its a bad drive or just disk errors.
Also, you'd be better off posting this in the powerbook section, you will recieve more responses there.