Hi I have a last Gen white 24inch C2D iMac, it came with 1gb of ram (2 512mbs). Recently I purchased two 1gb sticks, and replaced the two 512s with them. However I was wondering if I could use one of the 512s as well, and bring my total ram to 2.5gb. I ask this because I noticed only 2 slots for ram in my imac when I was replacing the ram, shouldn't there be three slots? Also can I use one of those 512mb sticks in my 2.33ghz macbook pro? Would the ram work with it? thanks!