About to buy a Macbook (even though I understand that many will counsel waiting until the update). Alas, I need it now. My question: Is there any reason (for serious writing, web browsing, and email) to go for the higher end processors or should I just buy the base model. I am thinking of battery life especially: do the higher end processors get better or worse battery life? Generally battery life is more important to me than processing speed. Thanks in advance.