I'm seeing a lot more used 3rd or 4th generation PowerBooks for sale. Is it better to buy one that is used and in "excellent" condition, or one that is covered by AppleCare but has been repaired. 1. If it's excellent and never needed repair - and even if it has AppleCare - then it should still be fine (maybe it wasn't a lemon); OR 2. If it's had to be repaired, then the parts that would have broken down have already been replaced by new components (e.g., logic board, optical drive) and so I should be more worry-free for that much longer. Any comments?