I have late 2008 silver macbook (1067 MHZ DDR3 RAM) which is starting to be really slow. I want to add more RAM and I also want to upgrade our 2010 27" imac RAM to 8GB. I was planning to buy 2x4GB for the Imac and using those 2x2GBs that came with the imac for my macbook. Can I do that? I do not want to get 4x2GB (would be the same price than 2x4GB) as eventually I want to add even more RAM to the imac which would make those 2GB RAMs useless for us. I mostly use Photoshop. Is there something else I can do to make sure my Macbook runs as smoothly as possible. I have noticed being slow just when opening programs. I used flatten & reinstall our PC to make it run better again. Is there something like that I can do for macs?