Considering adding some ram and a new HD to my MacBook. It's a late 2008 Unibody, 2.4 GHz. I currently have 4GB of Ram and a 250GB HD, which I believe spins at 5400 rpm (how do I check that?). My understanding is that this machine can take 6GB of ram. I'm assuming I can just buy one 4GB stick and replace the 2GB stick with it, correct? If so, where should I buy it from and what should I be looking for? Also, what performance increase can I expect - specifically in Photoshop CS5 and LR3? Will getting a faster spinning drive increase performance as well (for PS and LR)? If so, what should I be looking for there? Thanks for any/all help.