I recently acquired a Mid-2007 2.4gHz 20" iMac (738028K9X86). It currently has 3GB of RAM (one 1GB and one 2GB card). The official Apple maximum appears to be 4GB, but apparently 6GB works also. My question is... would it be better to take it to 4GB and have the cards equal in size (2 x 2GB) or take it to 6GB and have the cards unequal in size (one 2GB and one 4GB card)? Supposedly the system runs marginally faster with the cards 'balanced'. If anyone has any actual experience with performance I'd be interested in hearing about it. I normally run apps like photoshop, filemaker, browsers and the like.