A few caveats... I have a 21.5" Mid 2011 iMac with 2.7 GHz Intel Core i5. My main uses are as follows. Heavy web browsing Streaming video DVD playing Some writing Have had 8gb for over a year (2gb sticks x4) and haven't looked back. Just wondering if maybe I shouldn't at least think about getting 16gb or will 8gb be sufficient.