The reason that I am still on the old iMac OS 10.6 is that I am concerned about updating it. I am a enthusiastic user of iMac but have learned to stay away from any experimenting with software and certainly with an OS! When I absolutely follow instructions with all care, I still run in "steps-to-follow" that are just not to be found on the screen or totally different and then the problems start! My question is: is it possible to successfully update to a new OS like Yosemite 10.10, that is going to be available soon, without ending up with a iMac that doesn't function anymore? I have practically almost no experience in software operations. When e.g. I am required to first make a back up of the OS, I would not know how to do that. When things go wrong I would not know how to use this back up to correct the OS back to the old situation. I am capable of following to the point "step-by-step" instructions as long as these do tie-in with what I see on the screen, which often is not the case! (My iMac: Intel Core i7, memory 4GB) What is your experience with updating OS? How risky is this?