I am about to buy a 2013 21.5 inch iMac. I can go from a 2.7 processor to a 2.9 ($200 more than the lower end model.) Or, I can go from 8GB ram to 16GB for the same $200 increase. I do not have the money for both. I will be upgrading from the 1TB drive to a 1TB fusion . Although my 2008 iMac is a 2.8, it is dual core and uses a straight HD storage. I am sure the quad core and fusion drive alone will be peppier than what I have now. I use my computer primarily for internet surfing, office work and photography using Adobe Lightroom and Elements. My gut tells me the 16GB will be the better choice, that going from 2.7 to 2.9 will increase the speed, but I will likely not even notice it. But, my gut is often wrong. Thanks, Steven BTW: My question will be moot if I see a good buy in an Apple refurbished. I saw a machine with both 2.9 and 16 GB and fusion the other day for a great price, but I didn't pull the trigger fast enough.