I'm looking to upgrade my dying 27in 2010 iMac with a new 5K iMac but not sure if I should upgrade the processor and gpu. I'm hoping to get 5+ years out of it. My biggest use for the iMac is managing my 2TB+ iTunes library and using it as a media server. Beyond that it will be used for internet videos, web browsing, email, etc. I am not a video editor, photo editor (beyond basic touch ups and importing in iPhoto), and I do not play games on my computers. Is the base retina iMac good enough to last for my needs for the next few years? Should I just upgrade one or the other processor or GPU? I do plan on getting the 256gb SSD and keeping my media files on a USB 3.0 external hard drive.