After installing lion, I was noticing some very painful slowdowns and only being left with around 100megs of memory available at any given time. Decided to do the upgrade to 8gig (from 4) and needed more HDD space, so I went with the WD scorpio black 7200 RPM 750 gig. Did the install this weekend and it feels like I have a new machine. I know it doesn't compare to the quad core 2011 models, but it is a bit of a screamer in its own right currently. Just wanted to share a minor upgrade success story that has me back in love with my MBP and getting used to Lion. (even the 'natural scrolling', which is beginning to mess me up on my work PC, using the mouse scroll wheel) Really wish I could get a Mac at work. Sidenote, upon reinstalling the bottom panel, I could not get one of the screws to fasten fully. I don't know if the threads in the hole are boogered up or what, but I thought about getting a tap and chasing the threads to clean them up. I currently am missing the middle screw on the right side (by the HDD) I'm sorta OCD and want it put back in. Does anyone know the thread size of the machine screws they use?