So in about a month, I'm going to be buying a used 19" iMac from a co-worker. He has kept it up to date all the way up through Mountain Lion, which he bought from the Mac App Store. So here's my question--he's planning on reformatting it and putting Mountain Lion back on it, but I'm kind of wondering how that would work with the licensing. He bought Mountain Lion with his Apple ID/account/etc. Is that going to affect me at all when I start trying to set my iTunes and iCloud stuff up with my own IDs? Or am I going to end up having to buy Mountain Lion? Yes, the one non-Apple component left in my house--my old tower PC--time to put it to pasture. So excited!!! Anyone have anything else helpful they can tell me about buying a used Mac? This is going to be the first Mac I've ever purchased, but as you can tell I have everything else Apple makes, and I know my way around computers very well. Just trying to think of everything before I bring it home.