I have a OWC SSD as a main HD. Just ordered Optibay to put my 200GB of media (combo music and pics.) I have two options for storage lying around: 1) Seagate Momentus XT 500GB - pros: more area for storage, definitely faster. cons: firmware SD24 therefore HD never spins down, affecting the battery life; problem with video playback - has hiccups, a well known issue. 2) WD Scorpio black 320GB - pros: does spin down hence will have slightly better battery life - media, I imagine, won't be accessed as much, so spinning down and letting the HD go to sleep should help with battery life; smooth playback of videos cons: less storage space - but I do have drobo to throw all my old media files there if need be. I'm leaning towards WD for potential battery life and smooth playback though it's slower and having less storage space (120GB free vs 300GB) for the future is a somewhat big concern of mine - even if I have the drobo, I figure sometimes I want to hear some obscure music or see old pics out of random. Anyone want to chime in on decision making process?