Hi there, I just purchased a MacBook, have had it for less than a week. Overall, i'm loving it. It's much faster than my old iBook G4. I was using my Macbook today, and at about 8% battery left the computer just died (i though it was supposed to go to sleep). I then plugged in the computer and turned it back on. I went to system profiler and saw that the max capacity of my macbook went down from 5100 to 4496! I then freaked out, shut down my macbook and let it charge. After charging for a bit, I turned it back on and system profiler now shows the max at 5076. I'm using it now as it charges. What should I do to make sure the battery is working properly? Shouldn't the macbook have went to sleep? I'm worried the battery may be defective. Hopefully someone out there can help..thanks!