Customizing a mac: No way, Adding/changing hardware to your mac: No way, Mac OSX has a lot of security issue's because they refuse to update "older" systems in a few years and force you to buy a new version of Mac OSX, have you ever tried to bring your Mac to a place to fix it ? Have you seen the bill afterwards ? There is not much codecs available for Mac, Most opensource apps are there for windows and linux not for mac. Closed apps on MAC OSX tend to stay in background and not close at all which eats your resources. There is no way to re-use your old mac for instance as an Linux comtpuer/server, so you can throw away a machine that is not customizable which you paid too much for :)