A only needs to be boxed if it's going to be used as an object.  If you are
converting from a long to an int, it's a simple cast (in C#), and in fact
there are specific IL opcodes for those cases (conv.* opcodes).

Boxing takes a value type, then sticks it inside an object (hence the term
boxing).  This is needed if you do something that takes an object parameter,
and you're passing a valuetype.  The boxing happens automatically (for C#).
When you take it back out of an object, you unbox.  This requires you do a
cast, for instance int i = (int)myArrayList[0]; (C#).

So, you generally don't need to worry about what to do; the compiler will do
it for you or give you an error if it's an invalid cast and it can detect
it.

-mike
MVP