Originally Posted by Upstate

Upgrade-ability isn't so much an issue as fix-ability. If a part goes out on a traditional tower then it is easy to fix, but with an all in one you may have to bring it to the manufacturer or order special expensive parts from them. Even if you don't know what you are doing you can call up a buddy that does know about computers and buy them booze/steak instead of paying big bucks to a repair facility.