Hi, long time mac user but Macrumors newbie. I am looking to buy an iMac but do not want the gargantuan 27" screen. I prefer the 21.5", but I am concerned that they only offer the duo core chips. The top speed (3.33 gHz) is plenty fast for my purposes, I am just worried about obsolescence. I have a 5 year old powerbook G4 which is plenty fast for my purposes, but it is obsolete in the sense that newer webapplications and general software often will not work with powerpc chips. I am worried that the same will happen once the i5/i7 replace everything, which I assume will be pretty soon. Does anyone here that is more knowledgable than me know if this would be a problem similar to what I have now with the powerPC/intel duo core incompatabilities? I don't care if things will be a bit slower - my concern is that I won't even be able to run certain software in the future (which is the case with my PowerPC).