I just bought a new MacBook Air after owning a white Macbook for the last four years. I used to push that pretty hard, but I feel I'm still habituated towards quitting applications when I'm done with them, rather than keeping everything open. With the new MacBook I have two user accounts that I'm constantly switching back and forth between, and I run something like ten apps in each. Mail, iChat, Reeder, Safari, iWork, Skype, Twitter, iCal, iTunes, Grapher, and software called TestGen which I use to make worksheets and tests for my students is in my user account for work, and Mail, Ichat, Reeder, Skype, Twitter, iCal, iTunes, and Safari in my personal account. On the Macbook I used to quit out of the account before logging into another one, but so far the Air seems to handle both being logged in at the same time. Is this level of usage fairly normal? If most of the apps are in the background most of the time and none of them are particularly processor heavy, will this level of usage have a drastic negative effect on battery life?