How much would adding 4 GB of RAM to a 3.06 gHz dual-core iMac, bringing its total RAM to 8 GB, move its overall performance towards that of the 2.66 gHz quad-core i5 iMac with its standard 4 GB of RAM? I ask because doubling the RAM of the 3.06 gHz iMac with an after-market RAM chip, such as from Crucial, would raise its total cost to no more than that of the 2.66 gHz quad core. For example, Crucial sells a 4 GB chip for $250, and a pack of two 2-GB chips for $120; the 3.06 gHz costs about $250 less than the 2.66 gHz quad-core. How would that affect the relative performance of the two machines? Note: I'm buying on Amazon.com because I have quite of bit of Amazon.com gift certificates I wish to use. Also, I intend to keep my new iMac for a very long time. My old 667 mHz TiBook lasted 8 years. I don't wish to find myself locked out of future advances the way I was when I found that I could not use OS 10.5 on my TiBook because its chip was too slow.