I'm using an old Thinkpad x41 running Lubuntu 11.10. It has a new third party battery, 6 cell...the batt is now more than 1 year old now. I get well over 3 hours on a full charge. I'm pleased with this. Would be happy to put a future ubuntu on a future MacBook Air and get 6 hours of battery. That's about the only thing that might pry this x41 out of my hands.