Hi! I currently have a macbook pro that is going on 4 years old and I am looking to upgrade to either a MBP 15'' i7 or a 27'' iMac i7. I work as a university researcher and use both mac and windows applications - especially geographic information systems. I would love to improve the ergonomics of my workspace by adding a desktop display - I've just used my MBP display until now. So do I get a MBP with 24'' display or a 27'' iMac and use my old MBP for my portable needs? Thanks for your help upfront!!!