I'm in the market to have a back-up Mac. A Mac, whether MacBook or Mini that would only be used sparingly, perhaps to the tune of once every week or two for those tasks that iOS doesn't do well; that and for backing up photos taking from my iOS devices. I currently have a rMBP 13inch which I'm heavily considering ridding and wouldn't mind downgrading to a original white or black MacBook; or maybe even MacBook Pro's from before. As mentioned, I don't even need a fast Mac; just something that can tackle the things that iOS doesn't do well, for those random times when I need to enter certain sites. With that said, I'm checking eBay and other sites for low deals but can't help but wonder what features i've been accustomed to using may not be available on older models. Little things like Photo Stream and other OSX features are somewhat valuable to me, though i'm sure I wouldn't mind trimming some of the fat. I would like to see a list of MacBooks and the features and OS's they support and any guidance is truly appreciated.