Hi, I recently brought my new 27" iMac i7 to the genius bar because it was having all sorts of problems from the get go. To make a long story short, they decided it would be best to replace the machine altogether, but they had to ship it out to me. Anyway, the tech at the Genius Bar told me that my Mac was a little sluggish (jolting/skipping while scrolling through such apps as iPhoto) because I have been migrating since my iBook G4, and there are lots of broken files on my computer. I barely use the machine to its capacity. Thus, he told me to bring the new one in when I got it and he would help me with the migration process so I could avoid moving broken files that were slowing down my machine. However, if I can avoid lugging the 27" to the retail store again that would be great. Does anyone have any suggestions on how to easily, yet systematically, locate and remove broken files and the like? I downloaded an app like 'Clean My Mac', but the tech told me those were lousy, and weren't going to accomplish what I needed to do, hence still having the problem after running the app. Any good suggestions would be appreciated. I called Apple Care and the lady at tech support said I had to go through each file one by one . I need most of the documents from my old computer so I can't really start from scratch, unfortunately. Plus, my 100 GB currently used doesn't even scratch the surface of the 1TB hard drive. Thanks!