I'm running a Mac Mini 2009 as my main machine these days. It works well, but its slow at times. It takes about a minute or two to open a large >20MB power point files. But anyways, I'm thinking to get a used Mac Pro either from 2012 or 2013, I won't mind getting one from 2010 or 2011 since they will be cheaper. Can you guys advice on 1) Is the 2010 or 2011 one, good enough for the next few years? in terms of the ability to update and/or getting left out by Apple's new OS X down the road? 2) What is the best online place to purchase a used Mac pro (I'd like to avoid ebay type of purchase, unless is a reputable store on ebay). I found a Mac Pro 4,1 at my local university surplus the other day, and I was very tempted. But I'm also glad I didn't go for it because I realized after I got home that it will only take SATA II. So any advice?