I'm an engineering student. I really want my OS to run off a SSD, and all my most used applications. Therefore I will have a faster machine, no trouble there. What is a trouble though, is Apple's stubborn way of purchasing a SSD for your iMac. You can only do this through them without voiding your warranty, and with all the problems out there, the last thing I want to do is void my warranty. Would an external SSD do the job? I found this: http://www.bhphotovideo.com/c/product/642721-REG/G_Technology_GDM4_128_128GB_G_DRIVE_mini_SSD.html Could you give me any reviews or thoughts on this set up. Of course, if I got this external SSD. I would run my OS off this, and keep 1 TB hard drive for not as important files, designs, and drawings.