Hi, I have a friend who has an older iMac. From what I hear, it uses a DDR2 667 MHz and has two banks. It looks like only "Bank 0" is taken with 1 Gig. Can you tell me if any DDR2 667 SODIMM memory will work. Should I go for the 800 MHz to be safe? What's the capacity on these? 4 x 2? or 2 x 2? Thanks.