Hey, I've been considering exchanging my Gateway/Microsoft 17'' laptop for a 15'' Macbok Pro. I'm not sure I'm justified to go through with the purchase, though, haha. How often do you upgrade your laptop (not desktop)? My laptop has been holding up since 2010 but it overheats very easily (can't play a lot of Youtube videos at once) and as a result it shuts down nearly 4 times a day on average. Thankfully Google Chrome saves my browsing sessions. Additionally, in what price range could I expect to buy a refurbished non-retina display Macbook Pro? What ppi on a 15'' laptop would constitute retina display? What about a 17'' laptop? Do Macbooks overheat easily? Are they known to shut down when overheating?