I have the 27" iMac with 3.06 Intel Core 2 Duo, ATI Radeon 4670 256MB, and 12GB RAM. I only get occasional, minor stuttering / beachballs with 1080p and other stuff playing. I'm thinking of getting the $700 Mini and hook it up to Transcend 512GB external SSD (usb 3.0) for media. I'm a pretty average mac user--iTunes, Chrome, and occasional Youtube/Netflix/Hulu Plus. Would it do okay running 2560x1440 with Intel Iris Graphics? What would be the downgrades and upgrades? Please?