I have had my current 20 inch iMac since about 2006 and am very happy with it. For the most part it has been a problem free relationship and it still functions very well for what I ask of it. It is running 10.7.3 and has a 2.16 GHz Intel Core 2 Duo with 4 gig of RAM. My question is, what improvements can I expect with upgrading to the latest and greatest? I know the display will be larger and HD, and the machine will be a lot faster, but anything else? I don't currently run into any limitations with my iMac. I am able to do pretty much all that I want on it. I rip DVD's play music and TV, edit video and photography and surf the web etc. Nothing major. I have started to notice that it can't handle the HD video I am getting from some of my cameras (a contour+ shooting in 1080p 30ffps or 720p 60ffps) for instance. I know to expect speed improvements and I understand that Mountain Lion probably won't work on my iMac, but what else? Thanks!