Hi there, I'm having trouble choosing between two refurbished iMacs so I thought others might be able to shed some light on the matter. I'm deciding between a Refurbished 27-inch iMac 2.9GHz quad-core Intel Core i5 Originally released October 2012 8GB memory 1TB hard drive NVIDIA GeForce GTX 660M with 512MB At $1698 AND Refurbished iMac 27-inch 3.4GHz Quad-Core Intel Core i7 Originally released May 2011 4GB memory 1TB hard drive 8x SuperDrive (DVD±R DL/DVD±RW/CD-RW) AMD Radeon HD 6970M graphics with 1GB memory At $2149 I'd like to understand why the older iMac costs more but has less memory and how does the Radeon compare to the Nvidia. The cheaper iMac doesn't include a SuperDrive but I can get that for $89 so that's not an issue but having it separate is good should it breakdown I suppose? What's the difference between i5 and i7? I'd really appreciate any input to help clarify things, thanks!