Greetings everyone, this is my first post here. So I recently bought a mac (13" lower end pro) and decided to upgrade the memory and drive. I put in 4GB of Patriot matched DDR3 ram and also a Hitachi 320GB 7200 RPM drive. The memory went off without a hitch and works great, however the hard drive has been a different story. With the stock set up, I can unplug the machine and turn the brightness down to 1 and it will start telling me it has somewhere between 7 and 9 hours of battery life. I read on here from many posts that a 7200 RPM drive should have minimal impact on battery life. However, after installing the drive, the machine would indicate that it had only between 4.5 and 5.5 hrs of battery life. Furthermore, the whole machine had a buzzing feeling to it. I also noticed that with the stock drive, if I move the machine suddenly, the drive clicks (which I assume is a "head parking" technique to protect the platters), the new Hitachi doesn't do that. Upon investigation of the cases, I also noticed that the stock Hitachi drive (the 160GB one) says it has "Apple Firmware". So, has anyone else noticed the battery life thing? Also, is there something special about the firmware on the stock drive that helps battery life? Thanks and have a great day.