So, once again I have reached that stage where I have to throw out a Mac I am completely happy with, because the system cannot upgrade beyond Lion, and soon I'm sure Lion will stop receiving updates. Of course when that happens the security drops off, and numerous essential applications and browser plugins stop working. I am now shopping for a new desktop Mac, and it's longevity is my number 1 priority. I could pay a bit more (up to maybe one and a half thousand £ if necessary), but I only want to spend the extra money if it's likely to add more years to the computer's life span. Otherwise I'll be content with a low end Mac Mini. So what should I be looking at? The computer's year of release? It's processor type/speed? It's potential memory? And is buying a more expensive model usually a good bet in terms of longevity? How about a custom upgrade of the spec (e.g. Faster processor speed?) I know that nobody can say for sure how long a Mac will last, but any tips would be a much appreciated. Thanks in advance for any answers!