So, I have a few questions about the iMac 21.5" that comes with the Core i3 3.2 GHz. Does it come with hyper-threading? What separates that processor from the Core i5 3.6 GHz, apart from the increase in clock speed? In addition, how much better is the Radeon 5670 than the Radeon 4670? I'm trying to figure out how much worth it is to go for the next model up over the base model iMac.