I will be getting the 27 iMac in a few days but I need a little help. The most taxing thing I will be doing is some video encoding and video conferencing, the rest would fit into the norm stuff and no gaming. With an eye toward any upgrade stuff Apple might have in mind. My choices are: 3.4 GHz i5 1 TB Fusion GTX 780m 4GB or 3.2 GHz i5 1 TB Fusion GT 755m 1GB 1. is this fusion thing only really good for a few seconds of speed. if not what other good does it have over a regular 1 TB hard drive? 2. is the only plus with the GTX 780m for gaming? 3. this 2008, 24 inch model is going strong since I got it but I want this 27 to last even longer despite any upgrades to come. thanks.