Subject: Is there a limit to how much we can learn?

A friend of mine says that if you learn a new item, or remember something new,
this addition is at the expense of something you previously learned or remembered.  I don't think he's right but I'd be interested if there has been any
work to determine if there is some kind of andquot;upper limitandquot; to our brain's storage
capacity and (if so) what happens when you reach it. Is it right to think of human
memory as kind of a bio-computer andquot;hard diskandquot; of fixed capacity? 

Re: Is there a limit to how much we can learn?