I'm getting a standard i5 17" MBP and I want to boost my HDD with a Seagate Momentus Hybrid XT. However, it uses double the battery wattage and I've heard from ppl that a 7200rpm drive takes the battery life from 8 to 5 hours. Has anyone put in this drive or any 7200 drive and what kind of battery results have they gotten? I want to get 6 hours of battery life if I put it at 100% brightness and have safari running a few tabs, itunes, ical, mail, and word open. If anyone thinks the momentus hybrid will put me down at about 4 hours, I'll go with the WD scorpio blue 750GB, as it seems to be the most energy efficient hdd out there. Also, what kind of speed reduction can I expect between those two HDs as far as application performance, as I don't care about boot up time or app opening time. I'm also adding 8GB Ram if that affects anything.