Just on my way to work; wanted to quickly share my results from this morning. Screen brightness at 3/8, no wireless at all, no optical drive use, but continuous use (surfing, writing in Onenote, installing more programs) including 5 minutes of Unreal Tournament (lol... 35fps on medium settings @ 1024x768), and I transferred about 12gigs of data to the harddrive over the wired network. Results: Using only the main battery, from fully charged to critical level only (auto-standby, not auto-off), I got 4 hours and 15 minutes. I don't know how relevant this is for the average person, but I can say that for my future student uses, this amount of activity (i.e. a lot of harddrive activity) is probably more than I will experience in class taking notes. I won't be using wireless during note taking, and I won't be using the computer in general as hard as I did today... I am confident in 4 hours of class time no problem with just the main battery.