Which one uses the most battery? - Wifi, 3G or Bluetooth. I have pretty decent coverage where I am, so I don't turn on Wifi as much, but I'm wondering if my staying on 3G is consuming more battery life? Also, I love the fact that I can use the drop down and turn on/off Bluetooth. But, if it doesn't use any battery when its not connected, do I need to turn it off? I'd love some feedback. Thanks!