I am going to be purchasing my first MacBook Pro in the near future. One option I would like opinions on is the hard drive speed choice. Anyone that has had a hard drive upgrade with past MBPs observed a noticeable decrease in battery life for choosing a 7200 RPM hard drive over the 5400 RPM drive? I wouldn't do anything but casual web browsing via WIFI and use a bluetooth mouse or just run basic programs and not anything that is to CPU intensive when on battery power. Thank you in advance for your opinions.