I bought my iMac day one when the the aluminimum iMac's first went on sale. I believe that's coming up on about four years. I've enjoyed it, but I'm considering buying one of the new models. My current iMac is 19" (I believe, much smaller than the 27") Would appreciate feedback from some of you that made the leap from an older model to the current model. I'm sure the performance increase would be significant. I try not to be one that upgrades simply because a new model is available, but after three to four years I think it may be time.